code: func (prober *flexVolumeProber) Probe() (events []volume.ProbeEvent, err error) {
  	if prober.probeAllNeeded {
  		prober.testAndSetProbeAllNeeded(false)
  		return prober.probeAll()
  	}
  
  	return prober.probeMap()
  }
docs: // If probeAllNeeded is true, probe all pluginDir
  // else probe events in eventsMap