Renamed generateId method.
Removed redundant main() from AbstractMapper.
Updated PollMapper and UserMapper.
Added Answer implementation and AnswerMapper.
Check for null value of author field in PollMapper.
Added Commentary implementation and CommentaryMapper.
Vote and VoteMapper.
Forgot return statement from AnswerMapper#getDeleteStatement()
Added creation timestamps to Commentary and Vote.
Removed illegal setter from domain objects.