Autoset constants (Required fields having single valid enum value) Java (OkHttp) Implementation of #16547 (#16550)

* Autosets the parameters with the only value specified as enum if the parameter is also marked as required * Autosets the parameters with the only value specified as enum if the parameter is also marked as required * Autosets the parameters with the only value specified as enum if the parameter is also marked as required for Java default client. * Autosets the parameters with the only value specified as enum if the parameter is also marked as required for Java default client. * Autosets the parameters with the only value specified as enum if the parameter is also marked as required for Java default client. * Autosets the parameters with the only value specified as enum if the parameter is also marked as required for Java default client.
2025-10-14 00:13:50 +00:00 · 2023-09-15 12:11:17 +05:30 · 2023-09-15 12:11:17 +05:30 · 4b87606665
commit 4b87606665
parent d671fe24ee
28 changed files with 790 additions and 361 deletions
--- a/docs/generators/groovy.md
+++ b/docs/generators/groovy.md
@ -25,6 +25,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |apiPackage|package for generated api classes| |org.openapitools.api|
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-groovy|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java-camel.md
+++ b/docs/generators/java-camel.md
@ -30,6 +30,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
 |async|use async Callable controllers| |false|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |basePackage|base package (invokerPackage) for generated code| |org.openapitools|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
--- a/docs/generators/java-helidon-client.md
+++ b/docs/generators/java-helidon-client.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-java-client|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java-helidon-server.md
+++ b/docs/generators/java-helidon-server.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-java-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java-inflector.md
+++ b/docs/generators/java-inflector.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-inflector-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java-micronaut-client.md
+++ b/docs/generators/java-micronaut-client.md
@ -30,6 +30,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
 |authorizationFilterPattern|Configure the authorization filter pattern for the client. Generally defined when generating clients from multiple specification files| |null|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |basePathSeparator|Configure the separator to use between the application name and base path when referencing the property| |-|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
--- a/docs/generators/java-micronaut-server.md
+++ b/docs/generators/java-micronaut-server.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-micronaut|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |build|Specify for which build tool to generate files|<dl><dt>**gradle**</dt><dd>Gradle configuration is generated for the project</dd><dt>**all**</dt><dd>Both Gradle and Maven configurations are generated</dd><dt>**maven**</dt><dd>Maven configuration is generated for the project</dd></dl>|all|
--- a/docs/generators/java-msf4j.md
+++ b/docs/generators/java-msf4j.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-jaxrs-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java-pkmst.md
+++ b/docs/generators/java-pkmst.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |pkmst-microservice|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |basePackage|base package for java source code| |null|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
--- a/docs/generators/java-play-framework.md
+++ b/docs/generators/java-play-framework.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-java-playframework|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |basePackage|base package for generated code| |org.openapitools|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
--- a/docs/generators/java-undertow-server.md
+++ b/docs/generators/java-undertow-server.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-undertow-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java-vertx-web.md
+++ b/docs/generators/java-vertx-web.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-java-vertx-web-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0-SNAPSHOT|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java-vertx.md
+++ b/docs/generators/java-vertx.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-java-vertx-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0-SNAPSHOT|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/java.md
+++ b/docs/generators/java.md
@ -29,6 +29,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
 |asyncNative|If true, async handlers will be used, instead of the sync version| |false|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-cxf-cdi.md
+++ b/docs/generators/jaxrs-cxf-cdi.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-jaxrs-cxf-cdi-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-cxf-client.md
+++ b/docs/generators/jaxrs-cxf-client.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-jaxrs-client|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-cxf-extended.md
+++ b/docs/generators/jaxrs-cxf-extended.md
@ -28,6 +28,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-cxf-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-cxf.md
+++ b/docs/generators/jaxrs-cxf.md
@ -28,6 +28,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-cxf-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-jersey.md
+++ b/docs/generators/jaxrs-jersey.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-jaxrs-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-resteasy-eap.md
+++ b/docs/generators/jaxrs-resteasy-eap.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-jaxrs-resteasy-eap-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-resteasy.md
+++ b/docs/generators/jaxrs-resteasy.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-jaxrs-resteasy-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/jaxrs-spec.md
+++ b/docs/generators/jaxrs-spec.md
@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactId|artifactId in generated pom.xml. This also becomes part of the generated library's filename| |openapi-jaxrs-server|
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
 |camelCaseDollarSign|Fix camelCase when starting with $ sign. when true : $Value when false : $value| |false|
--- a/docs/generators/spring.md
+++ b/docs/generators/spring.md
@ -30,6 +30,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactUrl|artifact URL in generated pom.xml| |https://github.com/openapitools/openapi-generator|
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |1.0.0|
 |async|use async Callable controllers| |false|
+|autosetConstants|Automatically set Required Params having a Single enum value i.e. Constants in generated code| |false|
 |basePackage|base package (invokerPackage) for generated code| |org.openapitools|
 |bigDecimalAsString|Treat BigDecimal values as Strings to avoid precision loss.| |false|
 |booleanGetterPrefix|Set booleanGetterPrefix| |get|
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenOperation.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenOperation.java
@ -30,7 +30,7 @@ public class CodegenOperation {
            hasVersionHeaders = false, hasVersionQueryParams = false,
            isResponseBinary = false, isResponseFile = false, isResponseOptional = false, hasReference = false, defaultReturnType = false,
            isRestfulIndex, isRestfulShow, isRestfulCreate, isRestfulUpdate, isRestfulDestroy,
-            isRestful, isDeprecated, isCallbackRequest, uniqueItems, hasDefaultResponse = false,
+            isRestful, isDeprecated, isCallbackRequest, uniqueItems, hasDefaultResponse = false, hasConstantParams = false,
            hasErrorResponseObject; // if 4xx, 5xx responses have at least one error object defined
    public CodegenProperty returnProperty;
    public String path, operationId, returnType, returnFormat, httpMethod, returnBaseType,
@ -45,6 +45,7 @@ public class CodegenOperation {
    public List<CodegenParameter> queryParams = new ArrayList<CodegenParameter>();
    public List<CodegenParameter> headerParams = new ArrayList<CodegenParameter>();
    public List<CodegenParameter> implicitHeadersParams = new ArrayList<CodegenParameter>();
+    public List<CodegenParameter> constantParams = new ArrayList<CodegenParameter>();
    public List<CodegenParameter> formParams = new ArrayList<CodegenParameter>();
    public List<CodegenParameter> cookieParams = new ArrayList<CodegenParameter>();
    public List<CodegenParameter> requiredParams = new ArrayList<CodegenParameter>();
@ -392,6 +393,7 @@ public class CodegenOperation {
        sb.append(", operationIdLowerCase='").append(operationIdLowerCase).append('\'');
        sb.append(", operationIdCamelCase='").append(operationIdCamelCase).append('\'');
        sb.append(", operationIdSnakeCase='").append(operationIdSnakeCase).append('\'');
+        sb.append(", constantParams='").append(constantParams).append('\'');
        sb.append('}');
        return sb.toString();
    }
@ -472,7 +474,8 @@ public class CodegenOperation {
                Objects.equals(operationIdOriginal, that.operationIdOriginal) &&
                Objects.equals(operationIdLowerCase, that.operationIdLowerCase) &&
                Objects.equals(operationIdCamelCase, that.operationIdCamelCase) &&
-                Objects.equals(operationIdSnakeCase, that.operationIdSnakeCase);
+                Objects.equals(operationIdSnakeCase, that.operationIdSnakeCase) &&
+                Objects.equals(constantParams, that.constantParams);
    }

    @Override
@ -488,6 +491,6 @@ public class CodegenOperation {
                pathParams, queryParams, headerParams, formParams, cookieParams, requiredParams, returnProperty, optionalParams,
                authMethods, tags, responses, callbacks, imports, examples, requestBodyExamples, externalDocs,
                vendorExtensions, nickname, operationIdOriginal, operationIdLowerCase, operationIdCamelCase,
-                operationIdSnakeCase, hasErrorResponseObject, requiredAndNotNullableParams, notNullableParams);
+                operationIdSnakeCase, hasErrorResponseObject, requiredAndNotNullableParams, notNullableParams, constantParams);
    }
 }
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
@ -83,6 +83,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
    public static final String TEST_OUTPUT = "testOutput";
    public static final String IMPLICIT_HEADERS = "implicitHeaders";
    public static final String IMPLICIT_HEADERS_REGEX = "implicitHeadersRegex";
+    public static final String AUTOSET_CONSTANTS = "autosetConstants";
    public static final String JAVAX_PACKAGE = "javaxPackage";
    public static final String USE_JAKARTA_EE = "useJakartaEe";
    public static final String CONTAINER_DEFAULT_TO_NULL = "containerDefaultToNull";
@ -137,6 +138,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
    protected AnnotationLibrary annotationLibrary;
    protected boolean implicitHeaders = false;
    protected String implicitHeadersRegex = null;
+    protected boolean autosetConstants = false;
    protected boolean camelCaseDollarSign = false;
    protected boolean useJakartaEe = false;
    protected boolean containerDefaultToNull = false;
@ -277,6 +279,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
        cliOptions.add(CliOption.newBoolean(OPENAPI_NULLABLE, "Enable OpenAPI Jackson Nullable library", this.openApiNullable));
        cliOptions.add(CliOption.newBoolean(IMPLICIT_HEADERS, "Skip header parameters in the generated API methods using @ApiImplicitParams annotation.", implicitHeaders));
        cliOptions.add(CliOption.newString(IMPLICIT_HEADERS_REGEX, "Skip header parameters that matches given regex in the generated API methods using @ApiImplicitParams annotation. Note: this parameter is ignored when implicitHeaders=true"));
+        cliOptions.add(CliOption.newBoolean(AUTOSET_CONSTANTS, "Automatically set Required Params having a Single enum value i.e. Constants in generated code", autosetConstants));
        cliOptions.add(CliOption.newBoolean(CAMEL_CASE_DOLLAR_SIGN, "Fix camelCase when starting with $ sign. when true : $Value when false : $value"));
        cliOptions.add(CliOption.newBoolean(USE_JAKARTA_EE, "whether to use Jakarta EE namespace instead of javax"));
        cliOptions.add(CliOption.newBoolean(CONTAINER_DEFAULT_TO_NULL, "Set containers (array, set, map) default to null"));
@ -563,6 +566,10 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
            this.setImplicitHeadersRegex(additionalProperties.get(IMPLICIT_HEADERS_REGEX).toString());
        }

+        if (additionalProperties.containsKey(AUTOSET_CONSTANTS)) {
+            this.setAutosetConstants(Boolean.parseBoolean(additionalProperties.get(AUTOSET_CONSTANTS).toString()));
+        }
+
        if (additionalProperties.containsKey(CAMEL_CASE_DOLLAR_SIGN)) {
            this.setCamelCaseDollarSign(Boolean.parseBoolean(additionalProperties.get(CAMEL_CASE_DOLLAR_SIGN).toString()));
        }
@ -1578,6 +1585,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
            op.vendorExtensions.put("x-java-import", operationImports);

            handleImplicitHeaders(op);
+            handleConstantParams(op);
        }

        return objs;
@ -2052,6 +2060,10 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
        this.implicitHeadersRegex = implicitHeadersRegex;
    }

+    public void setAutosetConstants(boolean autosetConstants) {
+        this.autosetConstants = autosetConstants;
+    }
+
    public void setCamelCaseDollarSign(boolean camelCaseDollarSign) {
        this.camelCaseDollarSign = camelCaseDollarSign;
    }
@ -2294,6 +2306,45 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
        operation.hasParams = !operation.allParams.isEmpty();
    }

+    /**
+     * This method removes all constant Query, Header and Cookie Params from allParams and sets them as constantParams in the CodegenOperation.
+     * The definition of constant is single valued required enum params.
+     * The constantParams in the the generated code should be hardcoded to the constantValue if autosetConstants feature is enabled.
+     *
+     * @param operation - operation to be processed
+     */
+    protected void handleConstantParams(CodegenOperation operation) {
+        if (!autosetConstants || operation.allParams.isEmpty()) {            
+            return;
+        }
+        final ArrayList<CodegenParameter> copy = new ArrayList<>(operation.allParams);
+        // Remove all params from Params, Non constant params will be added back later.
+        operation.allParams.clear();
+
+        // Finds all constant params, removes them from allParams and adds them to constant params.
+        // Also, adds back non constant params to allParams.
+        for (CodegenParameter p : copy) {
+            if (p.isEnum && p.required && p._enum != null && p._enum.size() == 1) {
+                // Add to constantParams for use in the code generation templates. 
+                operation.constantParams.add(p);
+                if(p.isQueryParam) {
+                    operation.queryParams.removeIf(param -> param.baseName.equals(p.baseName));
+                }
+                if(p.isHeaderParam) {
+                    operation.headerParams.removeIf(param -> param.baseName.equals(p.baseName));
+                }
+                if(p.isCookieParam) {
+                    operation.cookieParams.removeIf(param -> param.baseName.equals(p.baseName));
+                }
+                LOGGER.info("Update operation [{}]. Remove parameter [{}] because it can only have a fixed value of [{}]", operation.operationId, p.baseName, p._enum.get(0));
+            } else {
+                // Add back to allParams as the param is not a constant.
+                operation.allParams.add(p);
+            }
+        }
+        operation.hasParams = !operation.allParams.isEmpty();
+    }
+
    private boolean shouldBeImplicitHeader(CodegenParameter parameter) {
        return StringUtils.isNotBlank(implicitHeadersRegex) && parameter.baseName.matches(implicitHeadersRegex);
    }
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/api.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/api.mustache
@ -172,18 +172,39 @@ public class {{classname}} {
        }

        {{/queryParams}}
+        {{#constantParams}}
+        {{#isQueryParam}}
+        // Set client side default value of Query Param "{{baseName}}".
+        localVarCollectionQueryParams.add(new Pair("{{baseName}}", {{#_enum}}"{{{.}}}"{{/_enum}}));
+
+        {{/isQueryParam}}
+        {{/constantParams}}
        {{#headerParams}}
        if ({{paramName}} != null) {
            localVarHeaderParams.put("{{baseName}}", localVarApiClient.parameterToString({{paramName}}));
        }

        {{/headerParams}}
+        {{#constantParams}}
+        {{#isHeaderParam}}
+        // Set client side default value of Header Param "{{baseName}}".
+        localVarHeaderParams.put("{{baseName}}", {{#_enum}}"{{{.}}}"{{/_enum}});
+
+        {{/isHeaderParam}}
+        {{/constantParams}}
        {{#cookieParams}}
        if ({{paramName}} != null) {
            localVarCookieParams.put("{{baseName}}", localVarApiClient.parameterToString({{paramName}}));
        }

        {{/cookieParams}}
+        {{#constantParams}}
+        {{#isCookieParam}}
+        // Set client side default value of Cookie Param "{{baseName}}".
+        localVarCookieParams.put("{{baseName}}", {{#_enum}}"{{{.}}}"{{/_enum}});
+
+        {{/isCookieParam}}
+        {{/constantParams}}
        {{/dynamicOperations}}
        {{#dynamicOperations}}
        localVarPath = localVarApiClient.fillParametersFromOperation(operation, paramMap, localVarPath, localVarQueryParams, localVarCollectionQueryParams, localVarHeaderParams, localVarCookieParams);
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java
--- a/modules/openapi-generator/src/test/resources/3_0/java/autoset_constant.yaml
+++ b/modules/openapi-generator/src/test/resources/3_0/java/autoset_constant.yaml
@ -0,0 +1,42 @@
+openapi: 3.0.3
+info:
+  title: Example Hello API
+  description: ''
+  version: v1
+servers:
+  - url: http://localhost
+    description: Global Endpoint
+paths:
+  /v1/hello/{name}:
+    get:
+      tags:
+        - hello_example
+      operationId: Hello
+      description: Say Hello
+      parameters:
+        - name: X-CUSTOM_CONSTANT_HEADER
+          in: header
+          required: true
+          schema:
+            type: string
+            enum:
+            - CONSTANT_VALUE
+        - name: name
+          in: path
+          required: true
+          schema:
+            type: string
+      responses:
+        default:
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/HelloResponse'
+components:
+  schemas:
+    HelloResponse:
+      type: object
+      properties:
+        message:
+          type: string