Gson.toJson() throw StackOverflowError when passing Intent

Question

I'm developing an app and on Android 6 (SDK 23) the code below goes into StackOverflow, but removing the putExtra() works correctly. Can you help me out?

Gson gson = new Gson();
Intent intent = new Intent(this, Clazz.class);
intent.putExtra("EXTRA", 2);
String json = gson.toJson(intent);