Thank you for your comments, Naganarasimha G R.
acceptNode => isRMRegisteredNode or isValidNode, former seems to be better
The logic of verifying nodes is to compare set of requested nodes to set of registered nodes, and check if former set is subset of the latter. The method acceptNode here is to compare one node to another(check if they are the same one). isRMRegiteredNode seems like compare one node to a set of nodes. I will trying to improve like this(maybe it is easier to understand).
seems like RMAdminCLI doesnt require both setYarnClient and createYarnClient.
setYarnClient is used only in testcase, where we need to have a mock yarnClient(like the property localNodeLabelsManager). I tried to set yarnClient to protected, and assigned it in test, it triggered another findbugs warning. I will trying to refine here, if you know some best practices, please tell me.