code: private Thread createServerThread(ServerTask r) {
          Thread t = new Thread(r);
          t.setName("EmbeddedLibertyServer-" + t.getName());
          return t;
      }
docs: The EmbeddedLibertyServer is not a daemon thread: if the server
  or framework is running, we want this process to stay awake. There
  are a lot of ways to get it unstuck... (or diagnose a hung
  server or whatever). But as soon as the framework does stop, then
  this thread will go away.
  
  @param r
  @return