code: @CanIgnoreReturnValue
    public long accumulateAndGet(K key, long x, LongBinaryOperator accumulatorFunction) {
      checkNotNull(accumulatorFunction);
      return updateAndGet(key, oldValue -> accumulatorFunction.applyAsLong(oldValue, x));
    }
docs: Updates the value currently associated with {@code key} by combining it with {@code x} via the
  specified accumulator function, returning the new value. The previous value associated with
  {@code key} (or zero, if there is none) is passed as the first argument to {@code
  accumulatorFunction}, and {@code x} is passed as the second argument.
  
  @since 21.0