presto-main/src/main/java/io/prestosql/operator/OuterLookupSource.java/OuterLookupSource/getJoinPosition
class OuterLookupSource:    @Override
    public long getJoinPosition(int position, Page hashChannelsPage, Page allChannelsPage)
    {
        return lookupSource.getJoinPosition(position, hashChannelsPage, allChannelsPage);
    }