presto-main/src/main/java/io/prestosql/operator/aggregation/histogram/GroupedTypedHistogram.java/BucketNodeFactory/groupAndValueMatches
class BucketNodeFactory:        private boolean groupAndValueMatches(long groupId, Block block, int position, int nodePointer, int valuePosition)
        {
            long existingGroupId = groupIds.get(nodePointer);

            return existingGroupId == groupId && type.equalTo(block, position, values, valuePosition);
        }