diff --git a/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache b/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
index 476e984fadc7..fc160bb14b92 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/modelGeneric.mustache
@@ -1,4 +1,4 @@
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 {{#hasImports}}
 import {
     {{#imports}}
@@ -46,17 +46,22 @@ export function {{classname}}FromJSON(json: any): {{classname}} {
         {{/isDate}}
         {{/isPrimitiveType}}
         {{^isPrimitiveType}}
-        {{#isContainer}}
+        {{#isListContainer}}
         '{{name}}': {{^required}}!exists(json, '{{baseName}}') ? undefined : {{/required}}(json['{{baseName}}'] as Array<any>).map({{#items}}{{datatype}}{{/items}}FromJSON),
-        {{/isContainer}}
-        {{^isContainer}}
+        {{/isListContainer}}
+        {{#isMapContainer}}
+        '{{name}}': {{^required}}!exists(json, '{{baseName}}') ? undefined : {{/required}}mapValues(json['{{baseName}}'], {{#items}}{{datatype}}{{/items}}FromJSON),
+        {{/isMapContainer}}
+        {{^isListContainer}}
+        {{^isMapContainer}}
         {{^isFreeFormObject}}
         '{{name}}': {{^required}}!exists(json, '{{baseName}}') ? undefined : {{/required}}{{datatype}}FromJSON(json['{{baseName}}']),
         {{/isFreeFormObject}}
         {{#isFreeFormObject}}
         '{{name}}': {{^required}}!exists(json, '{{baseName}}') ? undefined : {{/required}}json['{{baseName}}'],
         {{/isFreeFormObject}}
-        {{/isContainer}}
+        {{/isMapContainer}}
+        {{/isListContainer}}
         {{/isPrimitiveType}}
         {{/allVars}}
     };
@@ -78,17 +83,22 @@ export function {{classname}}ToJSON(value?: {{classname}}): any {
         '{{baseName}}': {{#isDate}}{{^required}}value.{{name}} === undefined ? undefined : {{/required}}value.{{name}}.toISOString().substr(0,10){{/isDate}}{{#isDateTime}}{{^required}}value.{{name}} === undefined ? undefined : {{/required}}value.{{name}}.toISOString(){{/isDateTime}}{{^isDate}}{{^isDateTime}}value.{{name}}{{/isDateTime}}{{/isDate}},
         {{/isPrimitiveType}}
         {{^isPrimitiveType}}
-        {{#isContainer}}
+        {{#isListContainer}}
         '{{baseName}}': {{^required}}value.{{name}} === undefined ? undefined : {{/required}}(value.{{name}} as Array<any>).map({{#items}}{{datatype}}{{/items}}ToJSON),
-        {{/isContainer}}
-        {{^isContainer}}
+        {{/isListContainer}}
+        {{#isMapContainer}}
+        '{{baseName}}': {{^required}}value.{{name}} === undefined ? undefined : {{/required}}mapValues(value.{{name}}, {{#items}}{{datatype}}{{/items}}ToJSON),
+        {{/isMapContainer}}
+        {{^isListContainer}}
+        {{^isMapContainer}}
         {{^isFreeFormObject}}
         '{{baseName}}': {{datatype}}ToJSON(value.{{name}}),
         {{/isFreeFormObject}}
         {{#isFreeFormObject}}
         '{{baseName}}': value.{{name}},
         {{/isFreeFormObject}}
-        {{/isContainer}}
+        {{/isMapContainer}}
+        {{/isListContainer}}        
         {{/isPrimitiveType}}
         {{/isReadOnly}}
         {{/allVars}}
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 624feac809f8..6f8038f5bdf2 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/runtime.mustache
@@ -202,6 +202,13 @@ export function querystring(params: HTTPQuery, prefix: string = ''): string {
         .join('&');
 }
 
+export function mapValues(data: any, fn: (item: any) => any) {
+  return Object.keys(data).reduce(
+    (acc, key) => ({ ...acc, [key]: fn(data[key]) }),
+    {}
+  );
+}
+
 export interface RequestContext {
     fetch: FetchAPI;
     url: string;
diff --git a/samples/client/petstore/typescript-fetch/builds/default/models/Category.ts b/samples/client/petstore/typescript-fetch/builds/default/models/Category.ts
index 99df10e5f1a8..f8809dccbea3 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/models/Category.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/models/Category.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A category for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/default/models/ModelApiResponse.ts b/samples/client/petstore/typescript-fetch/builds/default/models/ModelApiResponse.ts
index 369973446b9a..8b8e2c45fecd 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/models/ModelApiResponse.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/models/ModelApiResponse.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * Describes the result of uploading an image resource
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/default/models/Order.ts b/samples/client/petstore/typescript-fetch/builds/default/models/Order.ts
index ef002a60fc9c..6ce0496794f6 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/models/Order.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/models/Order.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * An order for a pets from the pet store
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/default/models/Pet.ts b/samples/client/petstore/typescript-fetch/builds/default/models/Pet.ts
index 27de4cee46bf..770f991b89d9 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/models/Pet.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/models/Pet.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 import {
     Category,
     CategoryFromJSON,
diff --git a/samples/client/petstore/typescript-fetch/builds/default/models/Tag.ts b/samples/client/petstore/typescript-fetch/builds/default/models/Tag.ts
index a7dd45562096..7c8098f6dc01 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/models/Tag.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/models/Tag.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A tag for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/default/models/User.ts b/samples/client/petstore/typescript-fetch/builds/default/models/User.ts
index f42cf94d748d..fd7430063f1c 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/models/User.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/models/User.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A User who is purchasing from the pet store
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
index 3af222044b24..67a45b169fde 100644
--- a/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/default/runtime.ts
@@ -213,6 +213,13 @@ export function querystring(params: HTTPQuery, prefix: string = ''): string {
         .join('&');
 }
 
+export function mapValues(data: any, fn: (item: any) => any) {
+  return Object.keys(data).reduce(
+    (acc, key) => ({ ...acc, [key]: fn(data[key]) }),
+    {}
+  );
+}
+
 export interface RequestContext {
     fetch: FetchAPI;
     url: string;
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Category.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Category.ts
index 99df10e5f1a8..f8809dccbea3 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Category.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Category.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A category for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/models/ModelApiResponse.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/models/ModelApiResponse.ts
index 369973446b9a..8b8e2c45fecd 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/models/ModelApiResponse.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/models/ModelApiResponse.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * Describes the result of uploading an image resource
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Order.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Order.ts
index ef002a60fc9c..6ce0496794f6 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Order.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Order.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * An order for a pets from the pet store
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Pet.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Pet.ts
index 27de4cee46bf..770f991b89d9 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Pet.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Pet.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 import {
     Category,
     CategoryFromJSON,
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Tag.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Tag.ts
index a7dd45562096..7c8098f6dc01 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/models/Tag.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/models/Tag.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A tag for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/models/User.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/models/User.ts
index f42cf94d748d..fd7430063f1c 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/models/User.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/models/User.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A User who is purchasing from the pet store
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts b/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts
index 3af222044b24..67a45b169fde 100644
--- a/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/es6-target/runtime.ts
@@ -213,6 +213,13 @@ export function querystring(params: HTTPQuery, prefix: string = ''): string {
         .join('&');
 }
 
+export function mapValues(data: any, fn: (item: any) => any) {
+  return Object.keys(data).reduce(
+    (acc, key) => ({ ...acc, [key]: fn(data[key]) }),
+    {}
+  );
+}
+
 export interface RequestContext {
     fetch: FetchAPI;
     url: string;
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Category.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Category.ts
index 99df10e5f1a8..f8809dccbea3 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Category.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Category.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A category for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/ModelApiResponse.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/ModelApiResponse.ts
index 369973446b9a..8b8e2c45fecd 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/ModelApiResponse.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/ModelApiResponse.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * Describes the result of uploading an image resource
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Order.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Order.ts
index ef002a60fc9c..6ce0496794f6 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Order.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Order.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * An order for a pets from the pet store
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Pet.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Pet.ts
index 27de4cee46bf..770f991b89d9 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Pet.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Pet.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 import {
     Category,
     CategoryFromJSON,
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Tag.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Tag.ts
index a7dd45562096..7c8098f6dc01 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Tag.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/Tag.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A tag for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/User.ts b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/User.ts
index f42cf94d748d..fd7430063f1c 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/User.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/models/User.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A User who is purchasing from the pet store
  * @export
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 3af222044b24..67a45b169fde 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-interfaces/runtime.ts
@@ -213,6 +213,13 @@ export function querystring(params: HTTPQuery, prefix: string = ''): string {
         .join('&');
 }
 
+export function mapValues(data: any, fn: (item: any) => any) {
+  return Object.keys(data).reduce(
+    (acc, key) => ({ ...acc, [key]: fn(data[key]) }),
+    {}
+  );
+}
+
 export interface RequestContext {
     fetch: FetchAPI;
     url: string;
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Category.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Category.ts
index 99df10e5f1a8..f8809dccbea3 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Category.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Category.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A category for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/ModelApiResponse.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/ModelApiResponse.ts
index 369973446b9a..8b8e2c45fecd 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/ModelApiResponse.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/ModelApiResponse.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * Describes the result of uploading an image resource
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Order.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Order.ts
index ef002a60fc9c..6ce0496794f6 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Order.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Order.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * An order for a pets from the pet store
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Pet.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Pet.ts
index 27de4cee46bf..770f991b89d9 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Pet.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Pet.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 import {
     Category,
     CategoryFromJSON,
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Tag.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Tag.ts
index a7dd45562096..7c8098f6dc01 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Tag.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/Tag.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A tag for a pet
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/User.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/User.ts
index f42cf94d748d..fd7430063f1c 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/User.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/models/User.ts
@@ -11,7 +11,7 @@
  * Do not edit the class manually.
  */
 
-import { exists } from '../runtime';
+import { exists, mapValues } from '../runtime';
 /**
  * A User who is purchasing from the pet store
  * @export
diff --git a/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts b/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts
index 3af222044b24..67a45b169fde 100644
--- a/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts
+++ b/samples/client/petstore/typescript-fetch/builds/with-npm-version/runtime.ts
@@ -213,6 +213,13 @@ export function querystring(params: HTTPQuery, prefix: string = ''): string {
         .join('&');
 }
 
+export function mapValues(data: any, fn: (item: any) => any) {
+  return Object.keys(data).reduce(
+    (acc, key) => ({ ...acc, [key]: fn(data[key]) }),
+    {}
+  );
+}
+
 export interface RequestContext {
     fetch: FetchAPI;
     url: string;