Throw helpful exception when DNS entry for JournalNode cannot be resolved

Setting :
qjournal://cdh4master01:8485;cdh4master02:8485;cdh4worker03:8485/hdfscluster
cdh4master01 and cdh4master02 JournalNode up and running,
cdh4worker03 not yet provisionning (no DNS entrie)

With :
`hadoop namenode -format` fails with :
12/11/19 14:42:42 FATAL namenode.NameNode: Exception in namenode join
java.lang.IllegalArgumentException: Unable to construct journal, qjournal://cdh4master01:8485;cdh4master02:8485;cdh4worker03:8485/hdfscluster
at org.apache.hadoop.hdfs.server.namenode.FSEditLog.createJournal(FSEditLog.java:1235)
at org.apache.hadoop.hdfs.server.namenode.FSEditLog.initJournals(FSEditLog.java:226)
at org.apache.hadoop.hdfs.server.namenode.FSEditLog.initJournalsForWrite(FSEditLog.java:193)
at org.apache.hadoop.hdfs.server.namenode.NameNode.format(NameNode.java:745)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1099)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1204)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.apache.hadoop.hdfs.server.namenode.FSEditLog.createJournal(FSEditLog.java:1233)
... 5 more
Caused by: java.lang.NullPointerException
at org.apache.hadoop.hdfs.qjournal.client.IPCLoggerChannelMetrics.getName(IPCLoggerChannelMetrics.java:107)
at org.apache.hadoop.hdfs.qjournal.client.IPCLoggerChannelMetrics.create(IPCLoggerChannelMetrics.java:91)
at org.apache.hadoop.hdfs.qjournal.client.IPCLoggerChannel.<init>(IPCLoggerChannel.java:161)
at org.apache.hadoop.hdfs.qjournal.client.IPCLoggerChannel$1.createLogger(IPCLoggerChannel.java:141)
at org.apache.hadoop.hdfs.qjournal.client.QuorumJournalManager.createLoggers(QuorumJournalManager.java:353)
at org.apache.hadoop.hdfs.qjournal.client.QuorumJournalManager.createLoggers(QuorumJournalManager.java:135)
at org.apache.hadoop.hdfs.qjournal.client.QuorumJournalManager.<init>(QuorumJournalManager.java:104)
at org.apache.hadoop.hdfs.qjournal.client.QuorumJournalManager.<init>(QuorumJournalManager.java:93)
... 10 more

I suggest that if quorum is up format should not fails.