dart: remove typetransformer class in enums

Author: while-loop

modules/swagger-codegen/src/main/resources/dart/api_helper.mustache

@@ -42,7 +42,7 @@ String parameterToString(dynamic value) {
     {{#model}}
       {{#isEnum}}
   } else if (value is {{classname}}) {
-    return new {{classname}}TypeTransformer().encode(value).toString();
+    return {{classname}}.encode(value).toString();
       {{/isEnum}}
     {{/model}}
   {{/models}}

modules/swagger-codegen/src/main/resources/dart/enum.mustache

@@ -1,33 +1,30 @@
 class {{classname}} {
   /// The underlying value of this enum member.
-  final {{dataType}} value;
+  {{dataType}} value;
 
-  const {{classname}}._internal(this.value);
+  {{classname}}._internal(this.value);
 
   {{#allowableValues}}
     {{#enumVars}}
       {{#description}}
   /// {{description}}
       {{/description}}
-  static const {{classname}} {{name}} = const {{classname}}._internal({{{value}}});
+  static {{classname}} {{name}} = {{classname}}._internal({{{value}}});
     {{/enumVars}}
   {{/allowableValues}}
-}
-
-class {{classname}}TypeTransformer {
-
-  dynamic encode({{classname}} data) {
-    return data.value;
-  }
 
-  {{classname}} decode(dynamic data) {
+  {{classname}}.fromJson(dynamic data) {
     switch (data) {
-      {{#allowableValues}}
-        {{#enumVars}}
-      case {{{value}}}: return {{classname}}.{{name}};
-        {{/enumVars}}
-      {{/allowableValues}}
-      default: throw('Unknown enum value to decode: $data');
+    {{#allowableValues}}
+      {{#enumVars}}
+          case {{{value}}}: value = data; break;
+      {{/enumVars}}
+    {{/allowableValues}}
+    default: throw('Unknown enum value to decode: $data');
     }
   }
+
+  static dynamic encode({{classname}} data) {
+    return data.value;
+  }
 }