presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/PushPartialAggregationThroughExchange.java/PushPartialAggregationThroughExchange/PushPartialAggregationThroughExchange
class PushPartialAggregationThroughExchange:    public PushPartialAggregationThroughExchange(Metadata metadata)
    {
        this.metadata = requireNonNull(metadata, "metadata is null");
    }