starting write proxy failed due to the optional "la" be assumed a MUST arg

I just built a release package followed by http://distributedlog.incubator.apache.org/docs/latest/deployment/cluster,

I failed at "Run write proxy" due to this error from output:

Exception in thread "main" java.lang.IllegalStateException: Optional.get() cannot be called on an absent value
at com.google.common.base.Absent.get(Absent.java:47)
at org.apache.distributedlog.service.DistributedLogServer.runServer(DistributedLogServer.java:189)
at org.apache.distributedlog.service.DistributedLogServer.runServer(DistributedLogServer.java:457)
at org.apache.distributedlog.service.DistributedLogServerApp.runCmd(DistributedLogServerApp.java:147)
at org.apache.distributedlog.service.DistributedLogServerApp.run(DistributedLogServerApp.java:89)
at org.apache.distributedlog.service.DistributedLogServerApp.main(DistributedLogServerApp.java:185)

we need to modify the log statement: "loadAppraiserClassStr.get()"