Read case and briefly answer (bullet points are fine)

Case 3: A unionized company in the Northeastern U.S. has given employees a $1000 Christmas bonus for the past 6 years. This bonus was not something that the union negotiated; it was simply something the employer chose to give to employees as a sign of gratitude and to increase employee satisfaction and motivation. This year, the employer has experienced dramatic decreases in profits and is not in a position to give the Christmas bonus. However, the union is arguing that the bonus cannot be eliminated without bargaining with the union. Question: 1) Is the Christmas bonus a mandatory bargaining issue in this situation, or can the employer unilaterally decide to stop the bonus? Explain