Handle exception while determining isController flag in KafkaMonitorImpl

[deneskelemen]

Sometimes, the clusterDescription.controller is null, and in such cases, the Cluster Overview does not appear.

We have tested this in several of our environments. We have not found any issues that this could have caused.

[Bert-R]

Good point! According to the documentation, the controller yield null, if the controller ID is not yet known.

I've added a comment with a request to improve the code quality.

[Bert-R]

For maintainability, please extract the code into a separate method that is called here:

Suggested change

	boolean isController;
	try {
	isController = node.id() == clusterDescription.controller.id();
	} catch (Exception e) {
	LOG.error("Failed to determine if node is controller",e);
	isController = false;
	}
	boolean isController = isController(node.id, clusterDescription);

In the method, check the controller rather than catching the NPE:

  private static boolean isController(int nodeId, DescribeClusterResult clusterDescription)
  {
    var controller = clusterDescription.controller;
    if (controller == null)
    {
      LOG.error("Controller ID not known yet");
      return false;
    }
    return nodeId == controller.id();
  }