public boolean retainAll(LongIterable source)
{
int oldSize = this.size();
final LongSet sourceSet = source instanceof LongSet ? (LongSet) source : source.toSet();
ByteLongHashMap retained = ByteLongHashMap.this.select(new ByteLongPredicate()
{
public boolean accept(byte key, long value)
{
return sourceSet.contains(value);
}