private boolean indexOutOfBounds(int position) {
    return position < 0 || position >= mAdapter.getItemCount();
  }
Determines if an item in the list should have a header that is different than the item in the
list that immediately precedes it. Items with no headers will always return false.

@param position of the list item in questions
@param isReverseLayout TRUE if layout manager has flag isReverseLayout
@return true if this item has a different header than the previous item in the list
library/src/main/java/com/timehop/stickyheadersrecyclerview/HeaderPositionCalculator.java