question: static int hash ( Object x1 , Object x2 , Object x3 , Object x4 ) { int h = 0 ; h ^= x1 . hashCode ( ) ; if ( x2 != null ) { h ^= x2 . hashCode ( ) ; } if ( x3 != null ) { h ^= x3 . hashCode ( ) ; } if ( x4 != null ) { h ^= x4 . hashCode ( ) ; } h += ~ ( h << 9 ) ; h ^= ( h > > > 14 ) ; h += ( h << 4 ) ; h ^= ( h > > > 10 ) ; return h ; }
target:  Returns a hash code for non-null Objects. Uses the same hash code spreader as most other java.util hash tables.