* @param stance The new <code>Stance</code>.
     * @param otherPlayer The <code>Player</code> wrt which the stance changes.
     * @param symmetric If true, change the otherPlayer stance as well.
     */
    public void changeStance(Player player, Stance stance,
                             Player otherPlayer, boolean symmetric) {
        ChangeSet cs = new ChangeSet();
        ServerPlayer serverPlayer = (ServerPlayer) player;
        if (serverPlayer.csChangeStance(stance, otherPlayer, symmetric, cs)) {
            sendToAll(cs);
        }
    }