presto-main/src/main/java/io/prestosql/operator/SetBuilderOperator.java/SetBuilderOperator/duplicate
class SetBuilderOperator:        @Override
        public OperatorFactory duplicate()
        {
            return new SetBuilderOperatorFactory(operatorId, planNodeId, setProvider.getType(), setChannel, hashChannel, expectedPositions, joinCompiler);
        }