From b5e2f5702d033adf5ef7ab0d9adffbd157116240 Mon Sep 17 00:00:00 2001
From: Georgy Ushakov <gush@equinor.com>
Date: Wed, 2 Jun 2021 21:29:44 +0200
Subject: [PATCH] Added support for async accessToken in typescript-fetch

---
 .../resources/typescript-fetch/apis.mustache  |  8 +---
 .../typescript-fetch/runtime.mustache         |  6 +--
 .../builds/default-v3.0/apis/FakeApi.ts       |  2 +-
 .../builds/default-v3.0/apis/PetApi.ts        | 48 ++++---------------
 .../builds/default-v3.0/runtime.ts            |  6 +--
 .../builds/default/apis/PetApi.ts             | 42 +++-------------
 .../builds/default/runtime.ts                 |  6 +--
 .../typescript-fetch/builds/enum/runtime.ts   |  6 +--
 .../builds/es6-target/src/apis/PetApi.ts      | 42 +++-------------
 .../builds/es6-target/src/runtime.ts          |  6 +--
 .../builds/multiple-parameters/apis/PetApi.ts | 42 +++-------------
 .../builds/multiple-parameters/runtime.ts     |  6 +--
 .../src/apis/PetApi.ts                        | 42 +++-------------
 .../src/runtime.ts                            |  6 +--
 .../typescript-three-plus/src/apis/PetApi.ts  | 42 +++-------------
 .../typescript-three-plus/src/runtime.ts      |  6 +--
 .../builds/with-interfaces/apis/PetApi.ts     | 42 +++-------------
 .../builds/with-interfaces/runtime.ts         |  6 +--
 .../with-npm-version/src/apis/PetApi.ts       | 42 +++-------------
 .../builds/with-npm-version/src/runtime.ts    |  6 +--
 .../without-runtime-checks/src/apis/PetApi.ts | 42 +++-------------
 .../without-runtime-checks/src/runtime.ts     |  6 +--
 22 files changed, 100 insertions(+), 360 deletions(-)

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 8466deb2853e..851b9ce3831e 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache
@@ -167,7 +167,7 @@ export class {{classname}} extends runtime.BaseAPI {
         {{#isBasicBearer}}
         if (this.configuration && this.configuration.accessToken) {
             const token = this.configuration.accessToken;
-            const tokenString = typeof token === 'function' ? token("{{name}}", [{{#scopes}}"{{{scope}}}"{{^-last}}, {{/-last}}{{/scopes}}]) : token;
+            const tokenString = await token("{{name}}", [{{#scopes}}"{{{scope}}}"{{^-last}}, {{/-last}}{{/scopes}}]);
 
             if (tokenString) {
                 headerParameters["Authorization"] = `Bearer ${tokenString}`;
@@ -192,11 +192,7 @@ export class {{classname}} extends runtime.BaseAPI {
         {{#isOAuth}}
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("{{name}}", [{{#scopes}}"{{{scope}}}"{{^-last}}, {{/-last}}{{/scopes}}]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("{{name}}", [{{#scopes}}"{{{scope}}}"{{^-last}}, {{/-last}}{{/scopes}}]);
         }
 
         {{/isOAuth}}
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 d0c29b93a755..e0498e0e316a 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
@@ -124,7 +124,7 @@ 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 | 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
 }
@@ -164,10 +164,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
diff --git a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeApi.ts b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeApi.ts
index 5985139ab238..31f05a52858a 100644
--- a/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default-v3.0/apis/FakeApi.ts
@@ -732,7 +732,7 @@ export class FakeApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             const token = this.configuration.accessToken;
-            const tokenString = typeof token === 'function' ? token("bearer_test", []) : token;
+            const tokenString = await token("bearer_test", []);
 
             if (tokenString) {
                 headerParameters["Authorization"] = `Bearer ${tokenString}`;
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 854c14d7dcd3..198794ce8b0b 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
@@ -87,11 +87,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -130,11 +126,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -173,11 +165,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -218,11 +206,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -296,11 +280,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -335,11 +315,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -396,11 +372,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -464,11 +436,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
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 cb001046c5b2..be992e2dac88 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
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
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 a219f15f7e2c..3bf150e489b6 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/apis/PetApi.ts
@@ -81,11 +81,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -124,11 +120,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -167,11 +159,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -212,11 +200,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -290,11 +274,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -329,11 +309,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -390,11 +366,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
diff --git a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
index f7a51f623ff2..20374a38659d 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
diff --git a/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts b/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts
index ccb0370bdc4a..d558d0ad7dee 100644
--- a/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/enum/runtime.ts
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
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 a219f15f7e2c..3bf150e489b6 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
@@ -81,11 +81,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -124,11 +120,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -167,11 +159,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -212,11 +200,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -290,11 +274,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -329,11 +309,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -390,11 +366,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
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 f7a51f623ff2..20374a38659d 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
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
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 4c47ea2e1f10..db5971d0ad5f 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
@@ -81,11 +81,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -124,11 +120,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -167,11 +159,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -212,11 +200,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -290,11 +274,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -329,11 +309,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -390,11 +366,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
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 f7a51f623ff2..20374a38659d 100644
--- a/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/multiple-parameters/runtime.ts
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
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 b98247c01daf..e2fd699fd73b 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
@@ -81,11 +81,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -124,11 +120,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -167,11 +159,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -212,11 +200,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -290,11 +274,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -329,11 +309,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -390,11 +366,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
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 f7a51f623ff2..20374a38659d 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
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
diff --git a/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/apis/PetApi.ts b/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/apis/PetApi.ts
index a219f15f7e2c..3bf150e489b6 100644
--- a/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/apis/PetApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/apis/PetApi.ts
@@ -81,11 +81,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -124,11 +120,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -167,11 +159,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -212,11 +200,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -290,11 +274,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -329,11 +309,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -390,11 +366,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
diff --git a/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/runtime.ts b/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/runtime.ts
index da5d9059bad3..95601f9e3076 100644
--- a/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/typescript-three-plus/src/runtime.ts
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
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 d7f8f8a62fe8..f8224fdb55f1 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
@@ -218,11 +218,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -261,11 +257,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -304,11 +296,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -349,11 +337,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -427,11 +411,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -466,11 +446,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -527,11 +503,7 @@ export class PetApi extends runtime.BaseAPI implements PetApiInterface {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
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 f7a51f623ff2..20374a38659d 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
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 a219f15f7e2c..3bf150e489b6 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
@@ -81,11 +81,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -124,11 +120,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -167,11 +159,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -212,11 +200,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -290,11 +274,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -329,11 +309,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -390,11 +366,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
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 f7a51f623ff2..20374a38659d 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
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }
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 dd0a9026b019..063d760e6ca5 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
@@ -77,11 +77,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -120,11 +116,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -163,11 +155,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -208,11 +196,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -286,11 +270,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const response = await this.request({
@@ -325,11 +305,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
@@ -386,11 +362,7 @@ export class PetApi extends runtime.BaseAPI {
 
         if (this.configuration && this.configuration.accessToken) {
             // oauth required
-            if (typeof this.configuration.accessToken === 'function') {
-                headerParameters["Authorization"] = this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
-            } else {
-                headerParameters["Authorization"] = this.configuration.accessToken;
-            }
+            headerParameters["Authorization"] = await this.configuration.accessToken("petstore_auth", ["write:pets", "read:pets"]);
         }
 
         const consumes: runtime.Consume[] = [
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 f7a51f623ff2..20374a38659d 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
@@ -135,7 +135,7 @@ 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 | 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
 }
@@ -175,10 +175,10 @@ export class Configuration {
         return undefined;
     }
 
-    get accessToken(): ((name: string, scopes?: string[]) => string) | undefined {
+    get accessToken(): ((name?: string, scopes?: string[]) => string | Promise<string>) | undefined {
         const accessToken = this.configuration.accessToken;
         if (accessToken) {
-            return typeof accessToken === 'function' ? accessToken : () => accessToken;
+            return typeof accessToken === 'function' ? accessToken : async () => accessToken;
         }
         return undefined;
     }