presto-main/src/main/java/io/prestosql/operator/aggregation/histogram/GroupedTypedHistogram.java/GroupedTypedHistogram/setGroupId
class GroupedTypedHistogram:    @Override
    public TypedHistogram setGroupId(long groupId)
    {
        // TODO: should we change all indices into buckets nodePointers to longs?
        this.currentGroupId = (int) groupId;
        return this;
    }