public static NavigableSet<String> getAllOnlineRegions(MiniHBaseCluster cluster)
    throws IOException {
    NavigableSet<String> online = new TreeSet<>();
    for (RegionServerThread rst : cluster.getLiveRegionServerThreads()) {
      try {
        for (RegionInfo region : ProtobufUtil
          .getOnlineRegions(rst.getRegionServer().getRSRpcServices())) {
          online.add(region.getRegionNameAsString());
        }
      } catch (RegionServerStoppedException e) {
        // That's fine.
      }
    }
    return online;
  }
This method clones the passed <code>c</code> configuration setting a new user into the clone.
Use it getting new instances of FileSystem. Only works for DistributedFileSystem w/o Kerberos.
@param c                     Initial configuration
@param differentiatingSuffix Suffix to differentiate this user from others.
@return A new configuration instance with a different user set into it.
hbase-testing-util/src/main/java/org/apache/hadoop/hbase/HBaseTestingUtility.java