If you want to keep your domain objects free from GSON annotations, this is a possible way to do this.

GsonBuilderForRenamingWitoutUsingGsonAnnotations

Gson gson = new GsonBuilder()
       .registerTypeAdapter(Date.class, new DateTypeAdapter())
       .setFieldNamingStrategy(new FieldNamingStrategy() {
           @Override
           public String translateName(Field f) {
               if (f.getName().equals("stars")) {
                   return "stargazers_count";
               } else if (f.getName().equals("repositories")) {
                   return "items";
               } else {
                   return FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES.translateName(f);
               }
           }
       })
       .create();