diff --git a/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache b/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache
index 9bed60ee16aa..8daa73e2783a 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache
@@ -191,13 +191,13 @@ export class {{classname}} extends runtime.BaseAPI {
         {{#isApiKey}}
         {{#isKeyInHeader}}
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["{{keyParamName}}"] = this.configuration.apiKey("{{keyParamName}}"); // {{name}} authentication
+            headerParameters["{{keyParamName}}"] = await this.configuration.apiKey("{{keyParamName}}"); // {{name}} authentication
         }
 
         {{/isKeyInHeader}}
         {{#isKeyInQuery}}
         if (this.configuration && this.configuration.apiKey) {
-            queryParameters["{{keyParamName}}"] = this.configuration.apiKey("{{keyParamName}}"); // {{name}} authentication
+            queryParameters["{{keyParamName}}"] = await this.configuration.apiKey("{{keyParamName}}"); // {{name}} authentication
         }
 
         {{/isKeyInQuery}}
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 6c625eb1c023..519050237520 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
@@ -11,7 +11,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -48,7 +48,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/allOf-nullable/runtime.ts b/samples/client/petstore/typescript-fetch/builds/allOf-nullable/runtime.ts
index 5bbe125fb671..0261d445a96c 100644
--- a/samples/client/petstore/typescript-fetch/builds/allOf-nullable/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/allOf-nullable/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/allOf-readonly/runtime.ts b/samples/client/petstore/typescript-fetch/builds/allOf-readonly/runtime.ts
index 5bbe125fb671..0261d445a96c 100644
--- a/samples/client/petstore/typescript-fetch/builds/allOf-readonly/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/allOf-readonly/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeClassnameTags123Api.ts b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeClassnameTags123Api.ts
index 59d4fa0cad84..e6f3fd1f0b96 100644
--- a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeClassnameTags123Api.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeClassnameTags123Api.ts
@@ -47,7 +47,7 @@ export class FakeClassnameTags123Api extends runtime.BaseAPI {
         headerParameters['Content-Type'] = 'application/json';
 
         if (this.configuration && this.configuration.apiKey) {
-            queryParameters["api_key_query"] = this.configuration.apiKey("api_key_query"); // api_key_query authentication
+            queryParameters["api_key_query"] = await this.configuration.apiKey("api_key_query"); // api_key_query authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/PetApi.ts
index 50584b111b1f..354aac42bbf8 100644
--- a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/PetApi.ts
@@ -250,7 +250,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/StoreApi.ts
index 19475d0ed9f3..3b17a1d7bb0d 100644
--- a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/default-v3.0/runtime.ts b/samples/client/petstore/typescript-fetch/builds/default-v3.0/runtime.ts
index f4720695347a..62bff92142aa 100644
--- a/samples/client/petstore/typescript-fetch/builds/default-v3.0/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default-v3.0/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/default/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/default/apis/PetApi.ts
index 1576f9cbba6e..5f507bceb566 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/apis/PetApi.ts
@@ -240,7 +240,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/default/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/default/apis/StoreApi.ts
index dd007df3588c..eda5a23e9a8f 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
index 9238a60cfe37..71ecdb875d14 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts b/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts
index 7bfa4c052756..cef607c3fcb5 100644
--- a/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/PetApi.ts
index 1576f9cbba6e..5f507bceb566 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/PetApi.ts
@@ -240,7 +240,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/StoreApi.ts
index dd007df3588c..eda5a23e9a8f 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/src/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/src/runtime.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/src/runtime.ts
index 9238a60cfe37..71ecdb875d14 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/src/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/src/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/PetApi.ts
index ffb7b3858af9..45628b2738d2 100644
--- a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/PetApi.ts
@@ -240,7 +240,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/StoreApi.ts
index d40d4aeceb06..97d90e388f30 100644
--- a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
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 9238a60cfe37..71ecdb875d14 100644
--- a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/PetApi.ts
index ecca2de78bed..47c11d68ca95 100644
--- a/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/PetApi.ts
@@ -240,7 +240,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/StoreApi.ts
index c51295bc1d03..3af1283917aa 100644
--- a/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/runtime.ts b/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/runtime.ts
index 9238a60cfe37..71ecdb875d14 100644
--- a/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/src/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/PetApi.ts
index 90fe9aecaf52..2f54dafe66e9 100644
--- a/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/PetApi.ts
@@ -355,7 +355,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/StoreApi.ts
index d40d4aeceb06..97d90e388f30 100644
--- a/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/runtime.ts b/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/runtime.ts
index 9238a60cfe37..71ecdb875d14 100644
--- a/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/sagas-and-records/src/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/FakeClassnameTags123Api.ts b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/FakeClassnameTags123Api.ts
index 59d4fa0cad84..e6f3fd1f0b96 100644
--- a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/FakeClassnameTags123Api.ts
+++ b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/FakeClassnameTags123Api.ts
@@ -47,7 +47,7 @@ export class FakeClassnameTags123Api extends runtime.BaseAPI {
         headerParameters['Content-Type'] = 'application/json';
 
         if (this.configuration && this.configuration.apiKey) {
-            queryParameters["api_key_query"] = this.configuration.apiKey("api_key_query"); // api_key_query authentication
+            queryParameters["api_key_query"] = await this.configuration.apiKey("api_key_query"); // api_key_query authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/PetApi.ts
index 50584b111b1f..354aac42bbf8 100644
--- a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/PetApi.ts
@@ -250,7 +250,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/StoreApi.ts
index 19475d0ed9f3..3b17a1d7bb0d 100644
--- a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/runtime.ts b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/runtime.ts
index f4720695347a..62bff92142aa 100644
--- a/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/snakecase-discriminator/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/PetApi.ts
index d11e216b3710..945aa959ca08 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/PetApi.ts
@@ -379,7 +379,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/StoreApi.ts
index c76e200d9349..cf68a43acd3c 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/apis/StoreApi.ts
@@ -151,7 +151,7 @@ export class StoreApi extends runtime.BaseAPI implements StoreApiInterface {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
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 9238a60cfe37..71ecdb875d14 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/PetApi.ts
index 1576f9cbba6e..5f507bceb566 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/PetApi.ts
@@ -240,7 +240,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/StoreApi.ts
index dd007df3588c..eda5a23e9a8f 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/apis/StoreApi.ts
@@ -80,7 +80,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/runtime.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/runtime.ts
index 9238a60cfe37..71ecdb875d14 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/src/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/with-string-enums/runtime.ts b/samples/client/petstore/typescript-fetch/builds/with-string-enums/runtime.ts
index 7bfa4c052756..cef607c3fcb5 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-string-enums/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-string-enums/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;
diff --git a/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/PetApi.ts
index 77f3d5c074b3..0aaabe7652a3 100644
--- a/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/PetApi.ts
@@ -234,7 +234,7 @@ export class PetApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/StoreApi.ts b/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/StoreApi.ts
index e43d223f7e1d..1b6199a07148 100644
--- a/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/StoreApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/apis/StoreApi.ts
@@ -76,7 +76,7 @@ export class StoreApi extends runtime.BaseAPI {
         const headerParameters: runtime.HTTPHeaders = {};
 
         if (this.configuration && this.configuration.apiKey) {
-            headerParameters["api_key"] = this.configuration.apiKey("api_key"); // api_key authentication
+            headerParameters["api_key"] = await this.configuration.apiKey("api_key"); // api_key authentication
         }
 
         const response = await this.request({
diff --git a/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/runtime.ts b/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/runtime.ts
index 722fd25f0107..f18e2d18a03c 100644
--- a/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/without-runtime-checks/src/runtime.ts
@@ -22,7 +22,7 @@ export interface ConfigurationParameters {
     queryParamsStringify?: (params: HTTPQuery) => string; // stringify function for query strings
     username?: string; // parameter for basic security
     password?: string; // parameter for basic security
-    apiKey?: string | ((name: string) => string); // parameter for apiKey security
+    apiKey?: string | Promise<string> | ((name: string) => string | Promise<string>); // parameter for apiKey security
     accessToken?: string | Promise<string> | ((name?: string, scopes?: string[]) => string | Promise<string>); // parameter for oauth2 security
     headers?: HTTPHeaders; //header params we want to use on every request
     credentials?: RequestCredentials; //value for the credentials param we want to use on each request
@@ -59,7 +59,7 @@ export class Configuration {
         return this.configuration.password;
     }
 
-    get apiKey(): ((name: string) => string) | undefined {
+    get apiKey(): ((name: string) => string | Promise<string>) | undefined {
         const apiKey = this.configuration.apiKey;
         if (apiKey) {
             return typeof apiKey === 'function' ? apiKey : () => apiKey;