diff --git a/modules/openapi-generator/src/main/resources/typescript-axios/configuration.mustache b/modules/openapi-generator/src/main/resources/typescript-axios/configuration.mustache
index 98585d783f4..575a42c020f 100644
--- a/modules/openapi-generator/src/main/resources/typescript-axios/configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-axios/configuration.mustache
@@ -5,7 +5,7 @@ export interface ConfigurationParameters {
     apiKey?: string | ((name: string) => string);
     username?: string;
     password?: string;
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     basePath?: string;
     baseOptions?: any;
 }
@@ -37,7 +37,7 @@ export class Configuration {
      * @param scopes oauth2 scope
      * @memberof Configuration
      */
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     /**
      * override base path
      * 
diff --git a/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache b/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
index 6878fd84958..0f80666ff9a 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
@@ -120,7 +120,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/modules/openapi-generator/src/main/resources/typescript-rxjs/runtime.mustache b/modules/openapi-generator/src/main/resources/typescript-rxjs/runtime.mustache
index 429584b64c3..27f466a6650 100644
--- a/modules/openapi-generator/src/main/resources/typescript-rxjs/runtime.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-rxjs/runtime.mustache
@@ -12,7 +12,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-axios/builds/default/configuration.ts b/samples/client/petstore/typescript-axios/builds/default/configuration.ts
index 65f9da218d6..e53e30f35e3 100644
--- a/samples/client/petstore/typescript-axios/builds/default/configuration.ts
+++ b/samples/client/petstore/typescript-axios/builds/default/configuration.ts
@@ -16,7 +16,7 @@ export interface ConfigurationParameters {
     apiKey?: string | ((name: string) => string);
     username?: string;
     password?: string;
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     basePath?: string;
     baseOptions?: any;
 }
@@ -48,7 +48,7 @@ export class Configuration {
      * @param scopes oauth2 scope
      * @memberof Configuration
      */
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     /**
      * override base path
      * 
diff --git a/samples/client/petstore/typescript-axios/builds/es6-target/configuration.ts b/samples/client/petstore/typescript-axios/builds/es6-target/configuration.ts
index 65f9da218d6..e53e30f35e3 100644
--- a/samples/client/petstore/typescript-axios/builds/es6-target/configuration.ts
+++ b/samples/client/petstore/typescript-axios/builds/es6-target/configuration.ts
@@ -16,7 +16,7 @@ export interface ConfigurationParameters {
     apiKey?: string | ((name: string) => string);
     username?: string;
     password?: string;
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     basePath?: string;
     baseOptions?: any;
 }
@@ -48,7 +48,7 @@ export class Configuration {
      * @param scopes oauth2 scope
      * @memberof Configuration
      */
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     /**
      * override base path
      * 
diff --git a/samples/client/petstore/typescript-axios/builds/with-complex-headers/configuration.ts b/samples/client/petstore/typescript-axios/builds/with-complex-headers/configuration.ts
index 65f9da218d6..e53e30f35e3 100644
--- a/samples/client/petstore/typescript-axios/builds/with-complex-headers/configuration.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-complex-headers/configuration.ts
@@ -16,7 +16,7 @@ export interface ConfigurationParameters {
     apiKey?: string | ((name: string) => string);
     username?: string;
     password?: string;
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     basePath?: string;
     baseOptions?: any;
 }
@@ -48,7 +48,7 @@ export class Configuration {
      * @param scopes oauth2 scope
      * @memberof Configuration
      */
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     /**
      * override base path
      * 
diff --git a/samples/client/petstore/typescript-axios/builds/with-interfaces/configuration.ts b/samples/client/petstore/typescript-axios/builds/with-interfaces/configuration.ts
index 65f9da218d6..e53e30f35e3 100644
--- a/samples/client/petstore/typescript-axios/builds/with-interfaces/configuration.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-interfaces/configuration.ts
@@ -16,7 +16,7 @@ export interface ConfigurationParameters {
     apiKey?: string | ((name: string) => string);
     username?: string;
     password?: string;
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     basePath?: string;
     baseOptions?: any;
 }
@@ -48,7 +48,7 @@ export class Configuration {
      * @param scopes oauth2 scope
      * @memberof Configuration
      */
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     /**
      * override base path
      * 
diff --git a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/configuration.ts b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/configuration.ts
index 65f9da218d6..e53e30f35e3 100644
--- a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/configuration.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/configuration.ts
@@ -16,7 +16,7 @@ export interface ConfigurationParameters {
     apiKey?: string | ((name: string) => string);
     username?: string;
     password?: string;
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     basePath?: string;
     baseOptions?: any;
 }
@@ -48,7 +48,7 @@ export class Configuration {
      * @param scopes oauth2 scope
      * @memberof Configuration
      */
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     /**
      * override base path
      * 
diff --git a/samples/client/petstore/typescript-axios/builds/with-npm-version/configuration.ts b/samples/client/petstore/typescript-axios/builds/with-npm-version/configuration.ts
index 65f9da218d6..e53e30f35e3 100644
--- a/samples/client/petstore/typescript-axios/builds/with-npm-version/configuration.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-npm-version/configuration.ts
@@ -16,7 +16,7 @@ export interface ConfigurationParameters {
     apiKey?: string | ((name: string) => string);
     username?: string;
     password?: string;
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     basePath?: string;
     baseOptions?: any;
 }
@@ -48,7 +48,7 @@ export class Configuration {
      * @param scopes oauth2 scope
      * @memberof Configuration
      */
-    accessToken?: string | ((name: string, scopes?: string[]) => string);
+    accessToken?: string | ((name?: string, scopes?: string[]) => string);
     /**
      * override base path
      * 
diff --git a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
index c95a101fbac..6feeddff5d4 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
@@ -131,7 +131,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts
index c95a101fbac..6feeddff5d4 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts
@@ -131,7 +131,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts
index c95a101fbac..6feeddff5d4 100644
--- a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts
@@ -131,7 +131,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
index c95a101fbac..6feeddff5d4 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
@@ -131,7 +131,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts
index c95a101fbac..6feeddff5d4 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts
@@ -131,7 +131,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-rxjs/builds/default/runtime.ts b/samples/client/petstore/typescript-rxjs/builds/default/runtime.ts
index ef017aff8fa..01e3bb106fe 100644
--- a/samples/client/petstore/typescript-rxjs/builds/default/runtime.ts
+++ b/samples/client/petstore/typescript-rxjs/builds/default/runtime.ts
@@ -23,7 +23,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-rxjs/builds/es6-target/runtime.ts b/samples/client/petstore/typescript-rxjs/builds/es6-target/runtime.ts
index ef017aff8fa..01e3bb106fe 100644
--- a/samples/client/petstore/typescript-rxjs/builds/es6-target/runtime.ts
+++ b/samples/client/petstore/typescript-rxjs/builds/es6-target/runtime.ts
@@ -23,7 +23,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-rxjs/builds/with-interfaces/runtime.ts b/samples/client/petstore/typescript-rxjs/builds/with-interfaces/runtime.ts
index ef017aff8fa..01e3bb106fe 100644
--- a/samples/client/petstore/typescript-rxjs/builds/with-interfaces/runtime.ts
+++ b/samples/client/petstore/typescript-rxjs/builds/with-interfaces/runtime.ts
@@ -23,7 +23,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {
diff --git a/samples/client/petstore/typescript-rxjs/builds/with-npm-version/runtime.ts b/samples/client/petstore/typescript-rxjs/builds/with-npm-version/runtime.ts
index ef017aff8fa..01e3bb106fe 100644
--- a/samples/client/petstore/typescript-rxjs/builds/with-npm-version/runtime.ts
+++ b/samples/client/petstore/typescript-rxjs/builds/with-npm-version/runtime.ts
@@ -23,7 +23,7 @@ export interface ConfigurationParameters {
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
     apiKey?: string | ((name: string) => string); // parameter for apiKey security
-    accessToken?: string | ((name: string, scopes?: string[]) => string); // parameter for oauth2 security
+    accessToken?: string | ((name?: string, scopes?: string[]) => string); // parameter for oauth2 security
 }
 
 export class Configuration {