diff --git a/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/json_serializable/class.mustache b/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/json_serializable/class.mustache
index 73e37f9c373e..1be71f5fbddb 100644
--- a/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/json_serializable/class.mustache
+++ b/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/json_serializable/class.mustache
@@ -59,11 +59,20 @@ class {{{classname}}} {
     required: {{#required}}true{{/required}}{{^required}}false{{/required}},
     includeIfNull: {{#required}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/required}}{{^required}}false{{/required}},{{^required}}{{#useOptional}}
     readValue: readOptionalValue,{{/useOptional}}{{/required}}
-  {{#isEnumOrRef}}
   {{#enumUnknownDefaultCase}}
+  {{#isArray}}
+  {{#items.isEnumOrRef}}
+  unknownEnumValue: {{{items.datatypeWithEnum}}}.unknownDefaultOpenApi,
+  {{/items.isEnumOrRef}}
+  {{/isArray}}
+  {{^isArray}}
+  {{^isMap}}
+  {{#isEnumOrRef}}
   unknownEnumValue: {{{datatypeWithEnum}}}.unknownDefaultOpenApi,
-  {{/enumUnknownDefaultCase}}
   {{/isEnumOrRef}}
+  {{/isMap}}
+  {{/isArray}}
+  {{/enumUnknownDefaultCase}}
   )
   {{/isBinary}}
   {{#isBinary}}
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/enum_arrays.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/enum_arrays.dart
index 70551bb1d4e6..26eea637873b 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/enum_arrays.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/enum_arrays.dart
@@ -43,7 +43,7 @@ class EnumArrays {
     name: r'array_enum',
     required: false,
     includeIfNull: false,
-  unknownEnumValue: List<EnumArraysArrayEnumEnum>.unknownDefaultOpenApi,
+  unknownEnumValue: EnumArraysArrayEnumEnum.unknownDefaultOpenApi,
   )
 
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/map_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/map_test.dart
index 7549af37b88b..0ae910b5e9fd 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/map_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/map_test.dart
@@ -46,7 +46,6 @@ class MapTest {
     name: r'map_of_enum_string',
     required: false,
     includeIfNull: false,
-  unknownEnumValue: Map<String, MapTestMapOfEnumStringEnum>.unknownDefaultOpenApi,
   )
 
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_duplicate_inline_enum.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_duplicate_inline_enum.dart
index 6b4bfc6b4b59..74c7e7bb302b 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_duplicate_inline_enum.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_duplicate_inline_enum.dart
@@ -29,7 +29,7 @@ class ObjectWithDuplicateInlineEnum {
     name: r'attribute',
     required: false,
     includeIfNull: false,
-  unknownEnumValue: Set<ObjectWithDuplicateInlineEnumAttributeEnum>.unknownDefaultOpenApi,
+  unknownEnumValue: ObjectWithDuplicateInlineEnumAttributeEnum.unknownDefaultOpenApi,
   )
 
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_inline_enum.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_inline_enum.dart
index 70d144a01c15..554a0f6add67 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_inline_enum.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake-json_serializable/lib/src/model/object_with_inline_enum.dart
@@ -29,7 +29,7 @@ class ObjectWithInlineEnum {
     name: r'attribute',
     required: false,
     includeIfNull: false,
-  unknownEnumValue: Set<ObjectWithInlineEnumAttributeEnum>.unknownDefaultOpenApi,
+  unknownEnumValue: ObjectWithInlineEnumAttributeEnum.unknownDefaultOpenApi,
   )