An internal review by Sean Busbey and Apekshit Sharma turned up a bunch of good findings going over HBASE-6721. They found some really good stuff a guava type is part of our public API and concurrency in a few core classes is inconsistent.
ServerName parsing from directory name should be more robust to errors from guava's HostAndPort
[RSGROUP] Master hosting regions messes up rsgroup calculation
Interface ReplicationEndpoint extends Guava's Service
Review Board (master)