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 74c0c77d712a..bbdf2edf4a35 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache
@@ -342,7 +342,7 @@ export class {{classname}} extends runtime.BaseAPI {
     }
     {{/useSingleRequestParameter}}
     {{#useSingleRequestParameter}}
-    async {{nickname}}({{#allParams.0}}requestParameters: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}Request, {{/allParams.0}}initOverrides?: RequestInit): Promise<{{{returnType}}}{{^returnType}}void{{/returnType}}> {
+    async {{nickname}}({{#allParams.0}}requestParameters: {{#prefixParameterInterfaces}}{{classname}}{{/prefixParameterInterfaces}}{{operationIdCamelCase}}Request{{^hasRequiredParams}} = {}{{/hasRequiredParams}}, {{/allParams.0}}initOverrides?: RequestInit): Promise<{{{returnType}}}{{^returnType}}void{{/returnType}}> {
         {{#returnType}}
         const response = await this.{{nickname}}Raw({{#allParams.0}}requestParameters, {{/allParams.0}}initOverrides);
         return await response.value();
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 19d5f89fce9c..b0a139e2f202 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
@@ -232,7 +232,7 @@ export class FakeApi extends runtime.BaseAPI {
     /**
      * Test serialization of outer boolean types
      */
-    async fakeOuterBooleanSerialize(requestParameters: FakeOuterBooleanSerializeRequest, initOverrides?: RequestInit): Promise<boolean> {
+    async fakeOuterBooleanSerialize(requestParameters: FakeOuterBooleanSerializeRequest = {}, initOverrides?: RequestInit): Promise<boolean> {
         const response = await this.fakeOuterBooleanSerializeRaw(requestParameters, initOverrides);
         return await response.value();
     }
@@ -261,7 +261,7 @@ export class FakeApi extends runtime.BaseAPI {
     /**
      * Test serialization of object with outer number type
      */
-    async fakeOuterCompositeSerialize(requestParameters: FakeOuterCompositeSerializeRequest, initOverrides?: RequestInit): Promise<OuterComposite> {
+    async fakeOuterCompositeSerialize(requestParameters: FakeOuterCompositeSerializeRequest = {}, initOverrides?: RequestInit): Promise<OuterComposite> {
         const response = await this.fakeOuterCompositeSerializeRaw(requestParameters, initOverrides);
         return await response.value();
     }
@@ -290,7 +290,7 @@ export class FakeApi extends runtime.BaseAPI {
     /**
      * Test serialization of outer number types
      */
-    async fakeOuterNumberSerialize(requestParameters: FakeOuterNumberSerializeRequest, initOverrides?: RequestInit): Promise<number> {
+    async fakeOuterNumberSerialize(requestParameters: FakeOuterNumberSerializeRequest = {}, initOverrides?: RequestInit): Promise<number> {
         const response = await this.fakeOuterNumberSerializeRaw(requestParameters, initOverrides);
         return await response.value();
     }
@@ -319,7 +319,7 @@ export class FakeApi extends runtime.BaseAPI {
     /**
      * Test serialization of outer string types
      */
-    async fakeOuterStringSerialize(requestParameters: FakeOuterStringSerializeRequest, initOverrides?: RequestInit): Promise<string> {
+    async fakeOuterStringSerialize(requestParameters: FakeOuterStringSerializeRequest = {}, initOverrides?: RequestInit): Promise<string> {
         const response = await this.fakeOuterStringSerializeRaw(requestParameters, initOverrides);
         return await response.value();
     }
@@ -683,7 +683,7 @@ export class FakeApi extends runtime.BaseAPI {
      * To test enum parameters
      * To test enum parameters
      */
-    async testEnumParameters(requestParameters: TestEnumParametersRequest, initOverrides?: RequestInit): Promise<void> {
+    async testEnumParameters(requestParameters: TestEnumParametersRequest = {}, initOverrides?: RequestInit): Promise<void> {
         await this.testEnumParametersRaw(requestParameters, initOverrides);
     }
 
diff --git a/samples/client/petstore/typescript-fetch/builds/enum/apis/DefaultApi.ts b/samples/client/petstore/typescript-fetch/builds/enum/apis/DefaultApi.ts
index 844842111c7a..6706d55addc9 100644
--- a/samples/client/petstore/typescript-fetch/builds/enum/apis/DefaultApi.ts
+++ b/samples/client/petstore/typescript-fetch/builds/enum/apis/DefaultApi.ts
@@ -94,7 +94,7 @@ export class DefaultApi extends runtime.BaseAPI {
 
     /**
      */
-    async fakeEnumRequestGetInline(requestParameters: FakeEnumRequestGetInlineRequest, initOverrides?: RequestInit): Promise<InlineResponse200> {
+    async fakeEnumRequestGetInline(requestParameters: FakeEnumRequestGetInlineRequest = {}, initOverrides?: RequestInit): Promise<InlineResponse200> {
         const response = await this.fakeEnumRequestGetInlineRaw(requestParameters, initOverrides);
         return await response.value();
     }
@@ -134,7 +134,7 @@ export class DefaultApi extends runtime.BaseAPI {
 
     /**
      */
-    async fakeEnumRequestGetRef(requestParameters: FakeEnumRequestGetRefRequest, initOverrides?: RequestInit): Promise<EnumPatternObject> {
+    async fakeEnumRequestGetRef(requestParameters: FakeEnumRequestGetRefRequest = {}, initOverrides?: RequestInit): Promise<EnumPatternObject> {
         const response = await this.fakeEnumRequestGetRefRaw(requestParameters, initOverrides);
         return await response.value();
     }
@@ -161,7 +161,7 @@ export class DefaultApi extends runtime.BaseAPI {
 
     /**
      */
-    async fakeEnumRequestPostInline(requestParameters: FakeEnumRequestPostInlineRequest, initOverrides?: RequestInit): Promise<InlineObject> {
+    async fakeEnumRequestPostInline(requestParameters: FakeEnumRequestPostInlineRequest = {}, initOverrides?: RequestInit): Promise<InlineObject> {
         const response = await this.fakeEnumRequestPostInlineRaw(requestParameters, initOverrides);
         return await response.value();
     }
@@ -188,7 +188,7 @@ export class DefaultApi extends runtime.BaseAPI {
 
     /**
      */
-    async fakeEnumRequestPostRef(requestParameters: FakeEnumRequestPostRefRequest, initOverrides?: RequestInit): Promise<EnumPatternObject> {
+    async fakeEnumRequestPostRef(requestParameters: FakeEnumRequestPostRefRequest = {}, initOverrides?: RequestInit): Promise<EnumPatternObject> {
         const response = await this.fakeEnumRequestPostRefRaw(requestParameters, initOverrides);
         return await response.value();
     }