presto-main/src/main/java/io/prestosql/sql/analyzer/Analysis.java/Analysis/getGroupingOperations
class Analysis:    public List<GroupingOperation> getGroupingOperations(QuerySpecification querySpecification)
    {
        return Optional.ofNullable(groupingOperations.get(NodeRef.of(querySpecification)))
                .orElse(emptyList());
    }