@CanIgnoreReturnValue
  @Override
  public final int add(@NullableDecl E element, int occurrences) {
    if (occurrences == 0) {
      return count(element);
    }
    checkArgument(occurrences > 0, "occurrences cannot be negative: %s", occurrences);
    int entryIndex = backingMap.indexOf(element);
    if (entryIndex == -1) {
      backingMap.put(element, occurrences);
      size += occurrences;
      return 0;
    }
    int oldCount = backingMap.getValue(entryIndex);
    long newCount = (long) oldCount + (long) occurrences;
    checkArgument(newCount <= Integer.MAX_VALUE, "too many occurrences: %s", newCount);
    backingMap.setValue(entryIndex, (int) newCount);
    size += occurrences;
    return oldCount;
  }
@CanIgnoreReturnValue
  @Override
  public final int add(@NullableDecl E element, int occurrences) {
    if (occurrences == 0) {
      return count(element);
    }
    checkArgument(occurrences > 0, "occurrences cannot be negative: %s", occurrences);
    int entryIndex = backingMap.indexOf(element);
    if (entryIndex == -1) {
      backingMap.put(element, occurrences);
      size += occurrences;
      return 0;
    }
    int oldCount = backingMap.getValue(entryIndex);
    long newCount = (long) oldCount + (long) occurrences;
    checkArgument(newCount <= Integer.MAX_VALUE, "too many occurrences: %s", newCount);
    backingMap.setValue(entryIndex, (int) newCount);
    size += occurrences;
    return oldCount;
  }
@ CanIgnoreReturnValue @ Override public final int add ( @ NullableDecl E element , int occurrences ) { if ( occurrences == 0 ) { return count ( element ) ; } checkArgument ( occurrences > 0 , "occurrences cannot be negative: %s" , occurrences ) ; int entryIndex = backingMap . indexOf ( element ) ; if ( entryIndex == - 1 ) { backingMap . put ( element , occurrences ) ; size += occurrences ; return 0 ; } int oldCount = backingMap . getValue ( entryIndex ) ; long newCount = ( long ) oldCount + ( long ) occurrences ; checkArgument ( newCount <= Integer . MAX_VALUE , "too many occurrences: %s" , newCount ) ; backingMap . setValue ( entryIndex , ( int ) newCount ) ; size += occurrences ; return oldCount ; }
{@inheritDoc}

@throws IllegalArgumentException if the call would result in more than {@link
Integer#MAX_VALUE} occurrences of {@code element} in this multiset.
{ @inheritDoc }