@CanIgnoreReturnValue
  public long getAndAdd(K key, long delta) {
    """
	Adds {@code delta} to the value currently associated with {@code key}, and returns the old
	value.
    """
    return getAndAccumulate(key, delta, Long::sum);
  }
@CanIgnoreReturnValue
  public long getAndAdd(K key, long delta) {
    return getAndAccumulate(key, delta, Long::sum);
  }
@ CanIgnoreReturnValue public long getAndAdd ( K key , long delta ) { return getAndAccumulate ( key , delta , Long :: sum ) ; }
Adds {@code delta} to the value currently associated with {@code key}, and returns the old
value.
Adds {