CustomScoreQueryBuilder.class working strangely.

CustomScoreQueryBuilder

package mypackage;

import org.elasticsearch.index.query.xcontent.BoolQueryBuilder;
import org.elasticsearch.index.query.xcontent.CustomScoreQueryBuilder;
import org.elasticsearch.index.query.xcontent.QueryBuilders;

public class Tryout {
	
	
	public static void main(String args[]) throws UnknownHostException, MongoException
	{
		BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
		boolQueryBuilder.boost(0);
		boolQueryBuilder.must( QueryBuilders.boostingQuery().positive( QueryBuilders.termQuery("a1", "b1")  ).negative( QueryBuilders.termQuery("c1", "d1") ).negativeBoost(0) );
		boolQueryBuilder.must( QueryBuilders.boostingQuery().positive( QueryBuilders.termQuery("a2", "b2")  ).negative( QueryBuilders.termQuery("c2", "d2") ).negativeBoost(1) );
		CustomScoreQueryBuilder customScoreQueryBuilder = QueryBuilders.customScoreQuery( boolQueryBuilder ).script("scoring");
		customScoreQueryBuilder.lang("native");
		customScoreQueryBuilder.params(null);
		System.out.println( customScoreQueryBuilder.buildAsUnsafeBytes() );
	}

}


Output of the code is
{
  "custom_score":
  {
    "query":
    {
      "bool":
     {
       "must":
      {
        "boosting":
          {
            "positive":
               {
                 "term":
                   {
                     "a1":"b1"
                   }
               },
               "negative":
                {
                    "term":
                    {
                       "c1":"d1"
                    }
                },
             "negative_boost":0.0
          },
          "must":
         {
             "boosting":
             {
                "positive":
                 {
                     "term":
                     {
                         "a2":"b2"
                     }
                 },
                 "negative":
                 {
                     "term":
                     {
                         "c2":"d2"
                     }
                },
                "negative_boost":1.0
             },
             "boost":0.0
          }
       },
       "script":"scoring",
       "lang":"native"
     }
    }
  }
}