def timestamp_attribute_name(obj, next_state, user_timestamp)
      user_timestamp == true ? default_timestamp_name(obj, next_state) : user_timestamp
    end
def timestamp_attribute_name(obj, next_state, user_timestamp)
      user_timestamp == true ? default_timestamp_name(obj, next_state) : user_timestamp
    end
Returns the name of the timestamp attribute for this event
 If the timestamp was simply true it returns the default_timestamp_name
 otherwise, returns the user-specified timestamp name