@Override
   public DefaultConsistentHash union(DefaultConsistentHash dch1, DefaultConsistentHash dch2) {
      return dch1.union(dch2);
   }
@ Override public DefaultConsistentHash union ( DefaultConsistentHash dch1 , DefaultConsistentHash dch2 ) { return dch1 . union ( dch2 ) ; }
Merges two consistent hash objects that have the same number of segments, numOwners and hash function.
For each segment, the primary owner of the first CH has priority, the other primary owners become backups.