presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/SetOperationNodeTranslator.java/SetOperationNodeTranslator/SetOperationNodeTranslator
class SetOperationNodeTranslator:    public SetOperationNodeTranslator(Metadata metadata, SymbolAllocator symbolAllocator, PlanNodeIdAllocator idAllocator)
    {
        this.symbolAllocator = requireNonNull(symbolAllocator, "SymbolAllocator is null");
        this.idAllocator = requireNonNull(idAllocator, "PlanNodeIdAllocator is null");
        requireNonNull(metadata, "metadata is null");
        this.countAggregation = metadata.resolveFunction(QualifiedName.of("count"), fromTypes(BOOLEAN));
    }