static synchronized MBeanServer createMBeanServer() {
    if (mbeanServer == null) {
      mbeanServer = MBeanServerFactory.createMBeanServer(DEFAULT_DOMAIN);
    }
    return mbeanServer;
  }
Create and configure (if necessary) and return the <code>MBeanServer</code> with which we will
be registering our <code>ModelMBean</code> implementations.

@see javax.management.MBeanServer
geode-core/src/main/java/org/apache/geode/admin/jmx/internal/MBeanUtils.java