private final int hash( Object k ) {
        int h = hashSeed;

        h ^= k.hashCode();

        h ^= ( h >>> 20 ) ^ ( h >>> 12 );
        return h ^ ( h >>> 7 ) ^ ( h >>> 4 );
    }
private final int hash( Object k ) {
        int h = hashSeed;

        h ^= k.hashCode();

        h ^= ( h >>> 20 ) ^ ( h >>> 12 );
        return h ^ ( h >>> 7 ) ^ ( h >>> 4 );
    }
private final int hash ( Object k ) { int h = hashSeed ; h ^= k . hashCode ( ) ; h ^= ( h >>> 20 ) ^ ( h >>> 12 ) ; return h ^ ( h >>> 7 ) ^ ( h >>> 4 ) ; }
Calculate the hash.
@param k key
@return
Calculate the hash .