presto-main/src/main/java/io/prestosql/operator/unnest/UnnestOperator.java/UnnestOperator/duplicate
class UnnestOperator:        @Override
        public OperatorFactory duplicate()
        {
            return new UnnestOperator.UnnestOperatorFactory(operatorId, planNodeId, replicateChannels, replicateTypes, unnestChannels, unnestTypes, withOrdinality, outer);
        }