A major bug in Play Services could be the reason GCM messages that you send aren't reaching your users. Pacemaker helps patch this bug by doing for Play Services what it should be doing on its own.
RecyclerView.Adapter that supports empty state, error state and loading state.
This library allows the implementation of questions that make use of checkboxes. The combination of a question and checkboxes allows for a customizable and elegant-looking UI.