one-off dartfmt

Author: kevmoo

json_serializable/lib/src/json_part_builder.dart

@@ -53,7 +53,8 @@ Builder jsonPartBuilder(
   return new PartBuilder([
     new JsonSerializableGenerator(useWrappers: useWrappers),
     const JsonLiteralGenerator()
-  ], header: header,
+  ],
+      header: header,
       // ignore: deprecated_member_use
       requireLibraryDirective: requireLibraryDirective);
 }