presto-main/src/main/java/io/prestosql/operator/MultiChannelGroupByHash.java/MultiChannelGroupByHash/contains
class MultiChannelGroupByHash:    @Override
    public boolean contains(int position, Page page, int[] hashChannels)
    {
        long rawHash = hashStrategy.hashRow(position, page);
        return contains(position, page, hashChannels, rawHash);
    }