code: function(a, b, aData, bData) {
          var queryA = this.hydrate(a),
              queryB = this.hydrate(b);
  
          var schema = this.schema;
          return queryA.merge(queryB, aData, bData, function(obj){
              return canReflect.getIdentity(obj, schema);
          });
      }
docs: unionMembers