static MBeanServer start() {
    if (!isStarted) {
      mbeanServer = createMBeanServer();
      registry = createRegistry();

      registerServerNotificationListener();
      createRefreshTimer();
      isStarted = true;
    }

    return mbeanServer;
  }
Initializes Mbean Server, Registry, Refresh Timer & registers Server Notification Listener.

@return reference to the mbeanServer
geode-core/src/main/java/org/apache/geode/admin/jmx/internal/MBeanUtils.java