question: public void mergeResponseFromShard ( int shardNumber , ResponseBuilder rb , List < NamedList < Object > > response ) { knownShards . set ( shardNumber ) ; if ( pivotFacetField == null ) { pivotFacetField = PivotFacetField . createFromListOfNamedLists ( shardNumber , rb , null , response ) ; } else { pivotFacetField . contributeFromShard ( shardNumber , rb , response ) ; } }
target:  Recursively merges the response from the specified shard, tracking the known shards.