presto-main/src/main/java/io/prestosql/operator/DistinctLimitOperator.java/DistinctLimitOperatorFactory/duplicate
class DistinctLimitOperatorFactory:        @Override
        public OperatorFactory duplicate()
        {
            return new DistinctLimitOperatorFactory(operatorId, planNodeId, sourceTypes, distinctChannels, limit, hashChannel, joinCompiler);
        }