@Override public int hashCode(){
  return Arrays.hashCode(new ImmutablePair[]{(ImmutablePair)first,(ImmutablePair)second});
}

@ Override public int hashCode ( ) { return Arrays . hashCode ( new ImmutablePair [ ] { ( ImmutablePair ) first , ( ImmutablePair ) second } ) ; }
returns a hash code value for this object .
