diff --git a/modules/openapi-generator/src/main/resources/typescript-nestjs/api.service.mustache b/modules/openapi-generator/src/main/resources/typescript-nestjs/api.service.mustache
index 4d2f116daf..d5dfcc0a10 100644
--- a/modules/openapi-generator/src/main/resources/typescript-nestjs/api.service.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-nestjs/api.service.mustache
@@ -121,7 +121,7 @@ export class {{classname}} {
         // authentication ({{name}}) required
 {{#isApiKey}}
 {{#isKeyInHeader}}
-        if (this.configuration.apiKeys["{{keyParamName}}"]) {
+        if (this.configuration.apiKeys?.["{{keyParamName}}"]) {
             headers['{{keyParamName}}'] = this.configuration.apiKeys["{{keyParamName}}"];
         }
 
@@ -130,7 +130,7 @@ export class {{classname}} {
         {{^hasQueryParams}}
         let queryParameters = new URLSearchParams();
         {{/hasQueryParams}}
-        if (this.configuration.apiKeys["{{keyParamName}}"]) {
+        if (this.configuration.apiKeys?.["{{keyParamName}}"]) {
             queryParameters.append('{{keyParamName}}', this.configuration.apiKeys["{{keyParamName}}"]);
         }
 
diff --git a/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/pet.service.ts
index ba76f58877..a28b44fc64 100644
--- a/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/pet.service.ts
@@ -255,7 +255,7 @@ export class PetService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
diff --git a/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/store.service.ts
index cadb5a9048..84b80c0f1d 100644
--- a/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/store.service.ts
@@ -85,7 +85,7 @@ export class StoreService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
diff --git a/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/user.service.ts
index 7cac2f8bf5..32ed0c7a5f 100644
--- a/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-nestjs-v6-provided-in-root/builds/default/api/user.service.ts
@@ -56,7 +56,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -101,7 +101,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -146,7 +146,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -191,7 +191,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -311,7 +311,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -355,7 +355,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
diff --git a/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/pet.service.ts
index 851eb41148..3a8c5f4125 100644
--- a/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/pet.service.ts
@@ -256,7 +256,7 @@ export class PetService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
diff --git a/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/store.service.ts
index 6b35126e5b..daae6d1dbe 100644
--- a/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/store.service.ts
@@ -86,7 +86,7 @@ export class StoreService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
diff --git a/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/user.service.ts
index f5e7a5ff5c..c34c9ae187 100644
--- a/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-nestjs-v8-provided-in-root/builds/default/api/user.service.ts
@@ -57,7 +57,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -102,7 +102,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -147,7 +147,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -192,7 +192,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -312,7 +312,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }
 
@@ -356,7 +356,7 @@ export class UserService {
         let headers = {...this.defaultHeaders};
 
         // authentication (api_key) required
-        if (this.configuration.apiKeys["api_key"]) {
+        if (this.configuration.apiKeys?.["api_key"]) {
             headers['api_key'] = this.configuration.apiKeys["api_key"];
         }