The static helper methods in NameNodes are used in hdfs-client module. For example, it's used by the DFSClient and NameNodeProxies classes which are being moved to hadoop-hdfs-client module. Meanwhile, we should keep the NameNode class itself in the hadoop-hdfs module.
This jira tracks the effort of moving the following static helper methods out of NameNode and thus hadoop-hdfs module. A good place to put these methods is the DFSUtilClient class:
Be cautious not to bring new checkstyle warnings.