Merge branch 'stable-2.15'

* stable-2.15:
  RestForwarder: Tidy up debug logging
  JGroupsPeerInfoProvider: Adjust javadoc and log output
  Compile against 2.15-rc1
  JGroupsPeerInfoProvider: Fix broken log formatting
  Improve the debug log when RestForwarder fails

Change-Id: Id16c39f2000b885c139606f046c658bbf4da6ee8