public static <T> SerializableComparator<Pair<T, ?>> byFirstOfPair(Comparator<? super T> comparator)
    {
        return new ByFirstOfPairComparator<T>(comparator);
    }
public static < T > SerializableComparator < Pair < T , ? > > byFirstOfPair ( Comparator < ? super T > comparator ) { return new ByFirstOfPairComparator < T > ( comparator ) ; }
Creates a comparator for pairs by using an existing comparator that only compares the first element of the pair

@param comparator original comparator that compares the first element of the pair
@return A comparator that compares pairs only by their first element