Fix Dart2 default template (#3790)

* fix dart2 default template

* update dart samples

samples/client/petstore/dart2/openapi/lib/model/api_response.dart

@@ -43,5 +43,16 @@ class ApiResponse {
     }
     return map;
   }
+
+  // maps a json object with a list of ApiResponse-objects as value to a dart map
+  static Map<String, List<ApiResponse>> mapListFromJson(Map<String, dynamic> json) {
+    var map = Map<String, List<ApiResponse>>();
+     if (json != null && json.isNotEmpty) {
+       json.forEach((String key, dynamic value) {
+         map[key] = ApiResponse.listFromJson(value);
+       });
+     }
+     return map;
+  }
 }
 

samples/client/petstore/dart2/openapi/lib/model/category.dart

@@ -38,5 +38,16 @@ class Category {
     }
     return map;
   }
+
+  // maps a json object with a list of Category-objects as value to a dart map
+  static Map<String, List<Category>> mapListFromJson(Map<String, dynamic> json) {
+    var map = Map<String, List<Category>>();
+     if (json != null && json.isNotEmpty) {
+       json.forEach((String key, dynamic value) {
+         map[key] = Category.listFromJson(value);
+       });
+     }
+     return map;
+  }
 }
 

samples/client/petstore/dart2/openapi/lib/model/order.dart

@@ -61,5 +61,16 @@ class Order {
     }
     return map;
   }
+
+  // maps a json object with a list of Order-objects as value to a dart map
+  static Map<String, List<Order>> mapListFromJson(Map<String, dynamic> json) {
+    var map = Map<String, List<Order>>();
+     if (json != null && json.isNotEmpty) {
+       json.forEach((String key, dynamic value) {
+         map[key] = Order.listFromJson(value);
+       });
+     }
+     return map;
+  }
 }
 

samples/client/petstore/dart2/openapi/lib/model/pet.dart

@@ -65,5 +65,16 @@ class Pet {
     }
     return map;
   }
+
+  // maps a json object with a list of Pet-objects as value to a dart map
+  static Map<String, List<Pet>> mapListFromJson(Map<String, dynamic> json) {
+    var map = Map<String, List<Pet>>();
+     if (json != null && json.isNotEmpty) {
+       json.forEach((String key, dynamic value) {
+         map[key] = Pet.listFromJson(value);
+       });
+     }
+     return map;
+  }
 }
 

samples/client/petstore/dart2/openapi/lib/model/tag.dart

@@ -38,5 +38,16 @@ class Tag {
     }
     return map;
   }
+
+  // maps a json object with a list of Tag-objects as value to a dart map
+  static Map<String, List<Tag>> mapListFromJson(Map<String, dynamic> json) {
+    var map = Map<String, List<Tag>>();
+     if (json != null && json.isNotEmpty) {
+       json.forEach((String key, dynamic value) {
+         map[key] = Tag.listFromJson(value);
+       });
+     }
+     return map;
+  }
 }
 

samples/client/petstore/dart2/openapi/lib/model/user.dart

@@ -68,5 +68,16 @@ class User {
     }
     return map;
   }
+
+  // maps a json object with a list of User-objects as value to a dart map
+  static Map<String, List<User>> mapListFromJson(Map<String, dynamic> json) {
+    var map = Map<String, List<User>>();
+     if (json != null && json.isNotEmpty) {
+       json.forEach((String key, dynamic value) {
+         map[key] = User.listFromJson(value);
+       });
+     }
+     return map;
+  }
 }