}

    frequency.add(-numberRemoved);
    size -= numberRemoved;
    return oldCount;
  }

  // Roughly a 33% performance improvement over AbstractMultiset.setCount().
  @CanIgnoreReturnValue
  @Override
  public int setCount(@ParametricNullness E element, int count) {
    checkNonnegative(count, "count");

    Count existingCounter;
    int oldCount;
    if (count == 0) {

  }

  @CanIgnoreReturnValue
  @Override
  public final int setCount(@ParametricNullness E element, int count) {
    checkNonnegative(count, "count");
    int oldCount = (count == 0) ? backingMap.remove(element) : backingMap.put(element, count);
    size += (count - oldCount);
    return oldCount;
  }

  @Override
  public final boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {