Artemis backup failover even quorum vote failed because of empty networkhealthcheck

[怀守昆]

 I'm test Artemis network isolation using quorum vote.

The backup failover after quorum vote return false.

I check the code find that in SharedNothingBackupQuorum#decideOnAction, after 
test isLiveDown(), networkHealthCheck is also checked.
If no network health check url/address configured, it always returns true.
So the backup decide it should failover.

Will this be an issue?

I use artemis 2.0.0, with 1 master and 1 slave.
According user guide, the backup should never failover.