presto-main/src/main/java/io/prestosql/operator/LookupJoinOperator.java/JoinProcessor/advanceProbePosition
class JoinProcessor:        private boolean advanceProbePosition(LookupSource lookupSource)
        {
            if (!probe.advanceNextPosition()) {
                clearProbe();
                return false;
            }

            // update join position
            joinPosition = probe.getCurrentJoinPosition(lookupSource);
            return true;
        }