Retrofit ships with a default converter for JSON that uses Gson but the library is content-format agnostic. The child modules contained herein are additional converters for other popular formats.
To use, supply an instance of your desired converter when building your RestAdapter
instance.
RestAdapter restAdapter = new RestAdapter.Builder()
.setServer("https://api.fake.google.com")
.setConverter(new ProtoConverter())
.build();