code: protected void introspect(ObjectName objectName, QueryExp query, PrintWriter writer) {
          // Iterate over the mbean servers, query for the beans, introspect
          for (MBeanServer mbeanServer : getMBeanServers()) {
              for (ObjectName mbean : mbeanServer.queryNames(objectName, query)) {
                  introspectMBeanAttributes(mbeanServer, mbean, writer);
              }
          }
      }
docs: GIven a JMX object name and a filter, introspect all matching
  MBeans that are found associated with registered MBean servers.
  
  @param objectName the object name pattern to provide
  to {@link javax.management.MBeanServer#queryNames(ObjectName, QueryExp)
  queryNames}
  @param query the query expression to provide to {@code queryNames}