presto-main/src/main/java/io/prestosql/operator/JoinHash.java/JoinHash/isJoinPositionEligible
class JoinHash:    @Override
    public boolean isJoinPositionEligible(long currentJoinPosition, int probePosition, Page allProbeChannelsPage)
    {
        return filterFunction == null || filterFunction.filter(toIntExact(currentJoinPosition), probePosition, allProbeChannelsPage);
    }