diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptAngularClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptAngularClientCodegen.java
index b701f304ac2..1dd1296e701 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptAngularClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptAngularClientCodegen.java
@@ -182,6 +182,7 @@ public class TypeScriptAngularClientCodegen extends AbstractTypeScriptClientCode
         supportingFiles.add(new SupportingFile("index.mustache", getIndexDirectory(), "index.ts"));
         supportingFiles.add(new SupportingFile("api.module.mustache", getIndexDirectory(), "api.module.ts"));
         supportingFiles.add(new SupportingFile("configuration.mustache", getIndexDirectory(), "configuration.ts"));
+        supportingFiles.add(new SupportingFile("api.base.service.mustache", getIndexDirectory(), "api.base.service.ts"));
         supportingFiles.add(new SupportingFile("variables.mustache", getIndexDirectory(), "variables.ts"));
         supportingFiles.add(new SupportingFile("encoder.mustache", getIndexDirectory(), "encoder.ts"));
         supportingFiles.add(new SupportingFile("param.mustache", getIndexDirectory(), "param.ts"));
@@ -411,7 +412,10 @@ public class TypeScriptAngularClientCodegen extends AbstractTypeScriptClientCode
                 hasSomeFormParams = true;
             }
             op.httpMethod = op.httpMethod.toLowerCase(Locale.ENGLISH);
-
+            // deduplicate auth methods by name (as they will lead to duplicate code):
+            op.authMethods =
+                op.authMethods != null ? op.authMethods.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(x -> x.name))), ArrayList::new))
+                    : null;
 
             // Prep a string buffer where we're going to set up our new version of the string.
             StringBuilder pathBuffer = new StringBuilder();
diff --git a/modules/openapi-generator/src/main/resources/typescript-angular/api.base.service.mustache b/modules/openapi-generator/src/main/resources/typescript-angular/api.base.service.mustache
new file mode 100644
index 00000000000..228cd66e09a
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/typescript-angular/api.base.service.mustache
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { {{configurationClassName}} } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: {{configurationClassName}};
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: {{configurationClassName}}) {
+        this.configuration = configuration || new {{configurationClassName}}();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache b/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
index ec3a695b91c..93d39bb3699 100644
--- a/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
@@ -16,6 +16,7 @@ import { {{ classname }} } from '{{ filename }}';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { {{configurationClassName}} }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 {{#withInterfaces}}
 import {
     {{classname}}Interface{{#useSingleRequestParameter}}{{#operations}}{{#operation}}{{#allParams.0}},
@@ -55,99 +56,14 @@ export interface {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterIn
 })
 {{/isProvidedInNone}}
 {{#withInterfaces}}
-export class {{classname}} implements {{classname}}Interface {
+export class {{classname}} extends BaseService implements {{classname}}Interface {
 {{/withInterfaces}}
 {{^withInterfaces}}
-export class {{classname}} {
+export class {{classname}} extends BaseService {
 {{/withInterfaces}}
 
-    protected basePath = '{{{basePath}}}';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new {{configurationClassName}}();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: {{configurationClassName}}) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-{{#hasSomeFormParams}}
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-{{/hasSomeFormParams}}
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        {{#isQueryParamObjectFormatJson}}
-        httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        {{/isQueryParamObjectFormatJson}}
-        {{^isQueryParamObjectFormatJson}}
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        {{/isQueryParamObjectFormatJson}}
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            {{#isQueryParamObjectFormatJson}}
-            if (key != null) {
-                httpParams = httpParams.append(key, JSON.stringify(value));
-            } else {
-                throw Error("key may not be null if value is a QueryParamObject");
-            }
-            {{/isQueryParamObjectFormatJson}}
-            {{^isQueryParamObjectFormatJson}}
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString(){{^isDateTime}}.substring(0, 10){{/isDateTime}});
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}{{#isQueryParamObjectFormatDot}}.{{/isQueryParamObjectFormatDot}}{{#isQueryParamObjectFormatKey}}[{{/isQueryParamObjectFormatKey}}${k}{{#isQueryParamObjectFormatKey}}]{{/isQueryParamObjectFormatKey}}` : k));
-            }
-            {{/isQueryParamObjectFormatJson}}
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: {{configurationClassName}}) {
+        super(httpClient, basePath, configuration);
     }
 
 {{#operation}}
@@ -213,10 +129,8 @@ export class {{classname}} {
         }
         {{/isArray}}
         {{^isArray}}
-        if ({{paramName}} !== undefined && {{paramName}} !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>{{paramName}}, '{{baseName}}');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>{{paramName}}, '{{baseName}}');
         {{/isArray}}
 {{/queryParams}}
 
@@ -236,60 +150,43 @@ export class {{classname}} {
 {{/headerParams}}
 
 {{#authMethods}}
-{{#-first}}
-        let localVarCredential: string | undefined;
-{{/-first}}
         // authentication ({{name}}) required
-        localVarCredential = this.configuration.lookupCredential('{{name}}');
-        if (localVarCredential) {
 {{#isApiKey}}
     {{#isKeyInHeader}}
-            localVarHeaders = localVarHeaders.set('{{keyParamName}}', localVarCredential);
+        localVarHeaders = this.configuration.addCredentialToHeaders('{{name}}', '{{keyParamName}}', localVarHeaders);
     {{/isKeyInHeader}}
     {{#isKeyInQuery}}
-            localVarQueryParameters = localVarQueryParameters.set('{{keyParamName}}', localVarCredential);
+        localVarQueryParameters = this.configuration.addCredentialToQuery('{{name}}', '{{keyParamName}}', localVarQueryParameters);
     {{/isKeyInQuery}}
 {{/isApiKey}}
 {{#isBasic}}
     {{#isBasicBasic}}
-            localVarHeaders = localVarHeaders.set('Authorization', 'Basic ' + localVarCredential);
+        localVarHeaders = this.configuration.addCredentialToHeaders('{{name}}', 'Authorization', localVarHeaders, 'Basic ');
     {{/isBasicBasic}}
     {{#isBasicBearer}}
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
+        localVarHeaders = this.configuration.addCredentialToHeaders('{{name}}', 'Authorization', localVarHeaders, 'Bearer ');
     {{/isBasicBearer}}
 {{/isBasic}}
 {{#isOAuth}}
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
+        localVarHeaders = this.configuration.addCredentialToHeaders('{{name}}', 'Authorization', localVarHeaders, 'Bearer ');
 {{/isOAuth}}
-        }
 
 {{/authMethods}}
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                {{#produces}}
-                '{{{mediaType}}}'{{^-last}},{{/-last}}
-                {{/produces}}
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+    {{#produces}}
+            '{{{mediaType}}}'{{^-last}},{{/-last}}
+    {{/produces}}
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
 {{#httpContextInOptions}}
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 {{/httpContextInOptions}}
 {{#httpTransferCacheInOptions}}
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 {{/httpTransferCacheInOptions}}
 
 {{#bodyParam}}
diff --git a/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache b/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache
index 39f73f8e2a5..6ad35011e07 100644
--- a/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-angular/configuration.mustache
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface {{configurationParametersInterfaceName}} {
@@ -187,6 +187,20 @@ export class {{configurationClassName}} {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientCodegenTest.java
index 9d07488018b..f2ab55f490a 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientCodegenTest.java
@@ -16,6 +16,7 @@ import org.testng.Assert;
 import org.testng.annotations.Test;
 
 import java.io.File;
+import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.HashMap;
@@ -390,4 +391,28 @@ public class TypeScriptAngularClientCodegenTest {
         assertThat(codegen.additionalProperties()).containsEntry("ngPackagrVersion", "19.0.0");
         assertThat(codegen.additionalProperties()).containsEntry("zonejsVersion", "0.15.0");
     }
+
+    @Test
+    public void testNoDuplicateAuthentication() throws IOException {
+        // GIVEN
+        final String specPath = "src/test/resources/3_0/spring/petstore-auth.yaml";
+
+        File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        // WHEN
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+            .setGeneratorName("typescript-angular")
+            .setInputSpec(specPath)
+            .setOutputDir(output.getAbsolutePath().replace("\\", "/"));
+
+        final ClientOptInput clientOptInput = configurator.toClientOptInput();
+
+        Generator generator = new DefaultGenerator();
+        generator.opts(clientOptInput).generate();
+
+        // THEN
+        final String fileContents = Files.readString(Paths.get(output + "/api/default.service.ts"));
+        assertThat(fileContents).containsOnlyOnce("localVarHeaders = this.configuration.addCredentialToHeaders('OAuth2', 'Authorization', localVarHeaders, 'Bearer ');");
+    }
 }
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/.openapi-generator/FILES b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/.openapi-generator/FILES
index 630a7ad821d..7115f7f67a8 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/.openapi-generator/FILES
+++ b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api.base.service.ts b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts
index 4fca3af0365..a7e2f0bd872 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts
+++ b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts
@@ -22,72 +22,17 @@ import { PetWithMappedDiscriminatorModel } from '../model/petWithMappedDiscrimin
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://api.example.xyz/v1';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -101,27 +46,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/configuration.ts b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/configuration.ts
index 526b454fb2b..788d6f1a9ee 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/configuration.ts
+++ b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -148,6 +148,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas/.openapi-generator/FILES b/samples/client/others/typescript-angular/builds/composed-schemas/.openapi-generator/FILES
index 630a7ad821d..7115f7f67a8 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas/.openapi-generator/FILES
+++ b/samples/client/others/typescript-angular/builds/composed-schemas/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas/api.base.service.ts b/samples/client/others/typescript-angular/builds/composed-schemas/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/others/typescript-angular/builds/composed-schemas/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts b/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts
index 4fca3af0365..a7e2f0bd872 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts
+++ b/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts
@@ -22,72 +22,17 @@ import { PetWithMappedDiscriminatorModel } from '../model/petWithMappedDiscrimin
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://api.example.xyz/v1';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -101,27 +46,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas/configuration.ts b/samples/client/others/typescript-angular/builds/composed-schemas/configuration.ts
index 526b454fb2b..788d6f1a9ee 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas/configuration.ts
+++ b/samples/client/others/typescript-angular/builds/composed-schemas/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -148,6 +148,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/.openapi-generator/FILES
index 6cf24d465b2..17c23e929b5 100644
--- a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/default.service.ts
diff --git a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts
index aee9f4bd8eb..c25f77b8cfc 100644
--- a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts
@@ -22,72 +22,17 @@ import { Fruit } from '../model/fruit';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class DefaultService {
+export class DefaultService extends BaseService {
 
-    protected basePath = 'http://localhost';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -101,22 +46,14 @@ export class DefaultService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -155,21 +92,13 @@ export class DefaultService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts
index 526b454fb2b..788d6f1a9ee 100644
--- a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -148,6 +148,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts
index d84622bd065..72ee45636c8 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'any'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -121,28 +53,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -200,28 +120,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -271,30 +179,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -346,30 +242,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -414,30 +298,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -480,28 +352,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -557,28 +417,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -646,29 +494,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts
index ec775facfa4..c5af33ebc1d 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'any'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -286,23 +203,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts
index 0d47d15dea5..b38da71ea68 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'any'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -173,21 +110,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -239,21 +168,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -306,21 +227,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -363,23 +276,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -425,34 +330,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -492,21 +385,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -554,21 +439,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts
index 8478feaad10..49c2d0b14ae 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -121,28 +53,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -200,28 +120,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -271,30 +179,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -346,30 +242,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -414,30 +298,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -480,28 +352,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -557,28 +417,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -646,29 +494,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts
index 899b1a44e87..a0fb6372769 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -286,23 +203,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts
index 22096fbb826..dbc7cbfba6f 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -173,21 +110,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -239,21 +168,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -306,21 +227,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -363,23 +276,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -425,34 +330,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -492,21 +385,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -554,21 +439,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/.openapi-generator/FILES
index 572424259e5..d1d45deee73 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api.base.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts
index 8478feaad10..49c2d0b14ae 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -121,28 +53,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -200,28 +120,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -271,30 +179,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -346,30 +242,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -414,30 +298,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -480,28 +352,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -557,28 +417,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -646,29 +494,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts
index 899b1a44e87..a0fb6372769 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -286,23 +203,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts
index 22096fbb826..dbc7cbfba6f 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -173,21 +110,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -239,21 +168,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -306,21 +227,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -363,23 +276,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -425,34 +330,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -492,21 +385,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -554,21 +439,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/.openapi-generator/FILES
index 6cf24d465b2..17c23e929b5 100644
--- a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/default.service.ts
diff --git a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts
index aee9f4bd8eb..c25f77b8cfc 100644
--- a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts
@@ -22,72 +22,17 @@ import { Fruit } from '../model/fruit';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class DefaultService {
+export class DefaultService extends BaseService {
 
-    protected basePath = 'http://localhost';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -101,22 +46,14 @@ export class DefaultService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -155,21 +92,13 @@ export class DefaultService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts
index 526b454fb2b..788d6f1a9ee 100644
--- a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -148,6 +148,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts
index d84622bd065..72ee45636c8 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'any'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -121,28 +53,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -200,28 +120,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -271,30 +179,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -346,30 +242,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -414,30 +298,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -480,28 +352,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -557,28 +417,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -646,29 +494,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts
index ec775facfa4..c5af33ebc1d 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'any'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -286,23 +203,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts
index 0d47d15dea5..b38da71ea68 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'any'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -173,21 +110,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -239,21 +168,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -306,21 +227,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -363,23 +276,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -425,34 +330,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -492,21 +385,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -554,21 +439,13 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts
index cb0904f147f..71c29cd700c 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,30 +54,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -204,28 +124,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -275,30 +183,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -350,30 +246,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -418,30 +302,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -485,30 +357,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -565,28 +425,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -655,29 +503,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts
index 603176dff00..3640d2bbfd1 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,23 +204,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts
index 54ee534e501..79188a67ed2 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,28 +52,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -182,28 +115,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -257,28 +178,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -332,28 +241,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -397,23 +294,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -460,34 +349,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -528,28 +405,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -597,28 +462,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/.openapi-generator/FILES
index 572424259e5..d1d45deee73 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api.base.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts
index cb0904f147f..71c29cd700c 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,30 +54,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -204,28 +124,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -275,30 +183,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -350,30 +246,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -418,30 +302,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -485,30 +357,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -565,28 +425,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -655,29 +503,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts
index 603176dff00..3640d2bbfd1 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,23 +204,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts
index 54ee534e501..79188a67ed2 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,28 +52,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -182,28 +115,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -257,28 +178,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -332,28 +241,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -397,23 +294,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -460,34 +349,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -528,28 +405,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -597,28 +462,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts
index cb0904f147f..71c29cd700c 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,30 +54,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -204,28 +124,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -275,30 +183,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -350,30 +246,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -418,30 +302,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -485,30 +357,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -565,28 +425,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -655,29 +503,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts
index 603176dff00..3640d2bbfd1 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,23 +204,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts
index 54ee534e501..79188a67ed2 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,28 +52,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -182,28 +115,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -257,28 +178,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -332,28 +241,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -397,23 +294,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -460,34 +349,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -528,28 +405,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -597,28 +462,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v14-query-param-object-format/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api.base.service.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts
index 918dfd782b9..09ff1c752e9 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts
@@ -24,74 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (key != null) {
-                httpParams = httpParams.append(key, JSON.stringify(value));
-            } else {
-                throw Error("key may not be null if value is a QueryParamObject");
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -111,30 +54,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -193,28 +124,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -264,30 +183,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -339,30 +246,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -407,30 +302,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -474,30 +357,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -554,28 +425,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -644,29 +503,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts
index 10507edad0b..3640d2bbfd1 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts
@@ -22,61 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (key != null) {
-                httpParams = httpParams.append(key, JSON.stringify(value));
-            } else {
-                throw Error("key may not be null if value is a QueryParamObject");
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -96,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -150,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -216,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -276,23 +204,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts
index 8e369a5ae6b..79188a67ed2 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts
@@ -22,61 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (key != null) {
-                httpParams = httpParams.append(key, JSON.stringify(value));
-            } else {
-                throw Error("key may not be null if value is a QueryParamObject");
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -96,28 +52,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -171,28 +115,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -246,28 +178,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -321,28 +241,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -386,23 +294,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -449,34 +349,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -517,28 +405,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -586,28 +462,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts
index cb0904f147f..71c29cd700c 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,30 +54,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -204,28 +124,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -275,30 +183,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -350,30 +246,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -418,30 +302,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -485,30 +357,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -565,28 +425,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -655,29 +503,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts
index 603176dff00..3640d2bbfd1 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,23 +204,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts
index 54ee534e501..79188a67ed2 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,28 +52,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -182,28 +115,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -257,28 +178,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -332,28 +241,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -397,23 +294,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -460,34 +349,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -528,28 +405,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -597,28 +462,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts
index cb0904f147f..71c29cd700c 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,30 +54,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -204,28 +124,16 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -275,30 +183,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -350,30 +246,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -418,30 +302,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -485,30 +357,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -565,28 +425,16 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -655,29 +503,17 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts
index 603176dff00..3640d2bbfd1 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,21 +52,13 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -161,29 +98,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -227,23 +152,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,23 +204,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts
index 54ee534e501..79188a67ed2 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,28 +52,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -182,28 +115,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -257,28 +178,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
@@ -332,28 +241,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -397,23 +294,15 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -460,34 +349,22 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -528,28 +405,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -597,28 +462,16 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts
index e4c401a2a64..cacb957ff10 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,35 +54,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -210,33 +127,18 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,35 +189,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -368,35 +255,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -442,35 +314,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -515,35 +372,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -601,33 +443,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -697,34 +524,19 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts
index b3ab6eb55b0..a00fa005329 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,26 +52,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -167,34 +101,19 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -239,28 +158,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -305,28 +213,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts
index 316ece2e354..a30d7ff38b2 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,33 +52,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -188,33 +118,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -269,33 +184,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -350,33 +250,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -421,28 +306,17 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -490,39 +364,24 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -564,33 +423,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -639,33 +483,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/.openapi-generator/FILES
index 6e213a61aa6..6cf79a289c8 100644
--- a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/pet.service.ts
index e4c401a2a64..cacb957ff10 100644
--- a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,35 +54,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -210,33 +127,18 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,35 +189,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -368,35 +255,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -442,35 +314,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -515,35 +372,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -601,33 +443,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -697,34 +524,19 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/store.service.ts
index b3ab6eb55b0..a00fa005329 100644
--- a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,26 +52,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -167,34 +101,19 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -239,28 +158,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -305,28 +213,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/user.service.ts
index 316ece2e354..a30d7ff38b2 100644
--- a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,33 +52,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -188,33 +118,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -269,33 +184,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -350,33 +250,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -421,28 +306,17 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -490,39 +364,24 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -564,33 +423,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -639,33 +483,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v18-provided-in-root/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/.openapi-generator/FILES
index 572424259e5..d1d45deee73 100644
--- a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/pet.service.ts
index e4c401a2a64..cacb957ff10 100644
--- a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,35 +54,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -210,33 +127,18 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,35 +189,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -368,35 +255,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -442,35 +314,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -515,35 +372,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -601,33 +443,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -697,34 +524,19 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/store.service.ts
index b3ab6eb55b0..a00fa005329 100644
--- a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,26 +52,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -167,34 +101,19 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -239,28 +158,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -305,28 +213,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/user.service.ts
index 316ece2e354..a30d7ff38b2 100644
--- a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,33 +52,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -188,33 +118,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -269,33 +184,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -350,33 +250,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -421,28 +306,17 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -490,39 +364,24 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -564,33 +423,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -639,33 +483,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v19-with-angular-dependency-params/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.
diff --git a/samples/client/petstore/typescript-angular-v19/builds/default/.openapi-generator/FILES b/samples/client/petstore/typescript-angular-v19/builds/default/.openapi-generator/FILES
index 572424259e5..d1d45deee73 100644
--- a/samples/client/petstore/typescript-angular-v19/builds/default/.openapi-generator/FILES
+++ b/samples/client/petstore/typescript-angular-v19/builds/default/.openapi-generator/FILES
@@ -1,5 +1,6 @@
 .gitignore
 README.md
+api.base.service.ts
 api.module.ts
 api/api.ts
 api/pet.service.ts
diff --git a/samples/client/petstore/typescript-angular-v19/builds/default/api.base.service.ts b/samples/client/petstore/typescript-angular-v19/builds/default/api.base.service.ts
new file mode 100644
index 00000000000..c0c316f1379
--- /dev/null
+++ b/samples/client/petstore/typescript-angular-v19/builds/default/api.base.service.ts
@@ -0,0 +1,69 @@
+import { HttpClient, HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
+import { CustomHttpParameterCodec } from './encoder';
+import { Configuration } from './configuration';
+
+export class BaseService {
+    protected basePath = '';
+    public defaultHeaders = new HttpHeaders();
+    public configuration: Configuration;
+    public encoder: HttpParameterCodec;
+
+    constructor(protected httpClient: HttpClient, basePath?: string|string[], configuration?: Configuration) {
+        this.configuration = configuration || new Configuration();
+        if (typeof this.configuration.basePath !== 'string') {
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
+            }
+
+            if (typeof basePath !== 'string') {
+                basePath = this.basePath;
+            }
+            this.configuration.basePath = basePath;
+        }
+        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
+    }
+
+    protected canConsumeForm(consumes: string[]): boolean {
+        return consumes.indexOf('multipart/form-data') !== -1;
+    }
+
+    protected addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
+        // If the value is an object (but not a Date), recursively add its keys.
+        if (typeof value === 'object' && !(value instanceof Date)) {
+            return this.addToHttpParamsRecursive(httpParams, value, key);
+        }
+        return this.addToHttpParamsRecursive(httpParams, value, key);
+    }
+
+    protected addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
+        if (value === null || value === undefined) {
+            return httpParams;
+        }
+        if (typeof value === 'object') {
+            // If JSON format is preferred, key must be provided.
+            if (key != null) {
+                return httpParams.append(key, JSON.stringify(value));
+            }
+            // Otherwise, if it's an array, add each element.
+            if (Array.isArray(value)) {
+                value.forEach(elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
+            } else if (value instanceof Date) {
+                if (key != null) {
+                    httpParams = httpParams.append(key, value.toISOString());
+                } else {
+                    throw Error("key may not be null if value is Date");
+                }
+            } else {
+                Object.keys(value).forEach(k => {
+                    const paramKey = key ? `${key}.${k}` : k;
+                    httpParams = this.addToHttpParamsRecursive(httpParams, value[k], paramKey);
+                });
+            }
+            return httpParams;
+        } else if (key != null) {
+            return httpParams.append(key, value);
+        }
+        throw Error("key may not be null if value is not object or array");
+    }
+}
diff --git a/samples/client/petstore/typescript-angular-v19/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v19/builds/default/api/pet.service.ts
index e4c401a2a64..cacb957ff10 100644
--- a/samples/client/petstore/typescript-angular-v19/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v19/builds/default/api/pet.service.ts
@@ -24,85 +24,17 @@ import { Pet } from '../model/pet';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class PetService {
+export class PetService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-    /**
-     * @param consumes string[] mime-types
-     * @return true: consumes contains 'multipart/form-data', false: otherwise
-     */
-    private canConsumeForm(consumes: string[]): boolean {
-        const form = 'multipart/form-data';
-        for (const consume of consumes) {
-            if (form === consume) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -122,35 +54,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -210,33 +127,18 @@ export class PetService {
             localVarHeaders = localVarHeaders.set('api_key', String(apiKey));
         }
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -287,35 +189,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -368,35 +255,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -442,35 +314,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -515,35 +372,20 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -601,33 +443,18 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
@@ -697,34 +524,19 @@ export class PetService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (petstore_auth) required
-        localVarCredential = this.configuration.lookupCredential('petstore_auth');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('petstore_auth', 'Authorization', localVarHeaders, 'Bearer ');
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
         // to determine the Content-Type header
         const consumes: string[] = [
diff --git a/samples/client/petstore/typescript-angular-v19/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v19/builds/default/api/store.service.ts
index b3ab6eb55b0..a00fa005329 100644
--- a/samples/client/petstore/typescript-angular-v19/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v19/builds/default/api/store.service.ts
@@ -22,72 +22,17 @@ import { Order } from '../model/order';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class StoreService {
+export class StoreService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,26 +52,15 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -167,34 +101,19 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -239,28 +158,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -305,28 +213,17 @@ export class StoreService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v19/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v19/builds/default/api/user.service.ts
index 316ece2e354..a30d7ff38b2 100644
--- a/samples/client/petstore/typescript-angular-v19/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v19/builds/default/api/user.service.ts
@@ -22,72 +22,17 @@ import { User } from '../model/user';
 // @ts-ignore
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
+import { BaseService } from '../api.base.service';
 
 
 
 @Injectable({
   providedIn: 'root'
 })
-export class UserService {
+export class UserService extends BaseService {
 
-    protected basePath = 'http://petstore.swagger.io/v2';
-    public defaultHeaders = new HttpHeaders();
-    public configuration = new Configuration();
-    public encoder: HttpParameterCodec;
-
-    constructor(protected httpClient: HttpClient, @Optional()@Inject(BASE_PATH) basePath: string|string[], @Optional() configuration: Configuration) {
-        if (configuration) {
-            this.configuration = configuration;
-        }
-        if (typeof this.configuration.basePath !== 'string') {
-            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
-            if (firstBasePath != undefined) {
-                basePath = firstBasePath;
-            }
-
-            if (typeof basePath !== 'string') {
-                basePath = this.basePath;
-            }
-            this.configuration.basePath = basePath;
-        }
-        this.encoder = this.configuration.encoder || new CustomHttpParameterCodec();
-    }
-
-
-    // @ts-ignore
-    private addToHttpParams(httpParams: HttpParams, value: any, key?: string): HttpParams {
-        if (typeof value === "object" && value instanceof Date === false) {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value);
-        } else {
-            httpParams = this.addToHttpParamsRecursive(httpParams, value, key);
-        }
-        return httpParams;
-    }
-
-    private addToHttpParamsRecursive(httpParams: HttpParams, value?: any, key?: string): HttpParams {
-        if (value == null) {
-            return httpParams;
-        }
-
-        if (typeof value === "object") {
-            if (Array.isArray(value)) {
-                (value as any[]).forEach( elem => httpParams = this.addToHttpParamsRecursive(httpParams, elem, key));
-            } else if (value instanceof Date) {
-                if (key != null) {
-                    httpParams = httpParams.append(key, (value as Date).toISOString().substring(0, 10));
-                } else {
-                   throw Error("key may not be null if value is Date");
-                }
-            } else {
-                Object.keys(value).forEach( k => httpParams = this.addToHttpParamsRecursive(
-                    httpParams, value[k], key != null ? `${key}.${k}` : k));
-            }
-        } else if (key != null) {
-            httpParams = httpParams.append(key, value);
-        } else {
-            throw Error("key may not be null if value is not object or array");
-        }
-        return httpParams;
+    constructor(protected httpClient: HttpClient, @Optional() @Inject(BASE_PATH) basePath: string|string[], @Optional() configuration?: Configuration) {
+        super(httpClient, basePath, configuration);
     }
 
     /**
@@ -107,33 +52,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -188,33 +118,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -269,33 +184,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
@@ -350,33 +250,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -421,28 +306,17 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -490,39 +364,24 @@ export class UserService {
         }
 
         let localVarQueryParameters = new HttpParams({encoder: this.encoder});
-        if (username !== undefined && username !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>username, 'username');
-        }
-        if (password !== undefined && password !== null) {
-          localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
-            <any>password, 'password');
-        }
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>username, 'username');
+        localVarQueryParameters = this.addToHttpParams(localVarQueryParameters,
+          <any>password, 'password');
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-                'application/xml',
-                'application/json'
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+            'application/xml',
+            'application/json'
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -564,33 +423,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         let responseType_: 'text' | 'json' | 'blob' = 'json';
@@ -639,33 +483,18 @@ export class UserService {
 
         let localVarHeaders = this.defaultHeaders;
 
-        let localVarCredential: string | undefined;
         // authentication (api_key) required
-        localVarCredential = this.configuration.lookupCredential('api_key');
-        if (localVarCredential) {
-            localVarHeaders = localVarHeaders.set('api_key', localVarCredential);
-        }
+        localVarHeaders = this.configuration.addCredentialToHeaders('api_key', 'api_key', localVarHeaders);
 
-        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
-        if (localVarHttpHeaderAcceptSelected === undefined) {
-            // to determine the Accept header
-            const httpHeaderAccepts: string[] = [
-            ];
-            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
-        }
+        const localVarHttpHeaderAcceptSelected: string | undefined = options?.httpHeaderAccept ?? this.configuration.selectHeaderAccept([
+        ]);
         if (localVarHttpHeaderAcceptSelected !== undefined) {
             localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
         }
 
-        let localVarHttpContext: HttpContext | undefined = options && options.context;
-        if (localVarHttpContext === undefined) {
-            localVarHttpContext = new HttpContext();
-        }
+        const localVarHttpContext: HttpContext = options?.context ?? new HttpContext();
 
-        let localVarTransferCache: boolean | undefined = options && options.transferCache;
-        if (localVarTransferCache === undefined) {
-            localVarTransferCache = true;
-        }
+        const localVarTransferCache: boolean = options?.transferCache ?? true;
 
 
         // to determine the Content-Type header
diff --git a/samples/client/petstore/typescript-angular-v19/builds/default/configuration.ts b/samples/client/petstore/typescript-angular-v19/builds/default/configuration.ts
index 4ad26d0bdcb..cd184034284 100644
--- a/samples/client/petstore/typescript-angular-v19/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-angular-v19/builds/default/configuration.ts
@@ -1,4 +1,4 @@
-import { HttpParameterCodec } from '@angular/common/http';
+import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { Param } from './param';
 
 export interface ConfigurationParameters {
@@ -168,6 +168,20 @@ export class Configuration {
             : value;
     }
 
+    public addCredentialToHeaders(credentialKey: string, headerName: string, headers: HttpHeaders, prefix?: string): HttpHeaders {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? headers.set(headerName, (prefix ?? '') + value)
+            : headers;
+    }
+
+    public addCredentialToQuery(credentialKey: string, paramName: string, query: HttpParams): HttpParams {
+        const value = this.lookupCredential(credentialKey);
+        return value
+            ? query.set(paramName, value)
+            : query;
+    }
+
     private defaultEncodeParam(param: Param): string {
         // This implementation exists as fallback for missing configuration
         // and for backwards compatibility to older typescript-angular generator versions.