@Override
  public String getClientIdAuditPrefix() {
    return "Client=" + RpcServer.getRequestUserName().orElse(null) + "/"
      + RpcServer.getRemoteAddress().orElse(null);
  }
Returns Client info for use as prefix on an audit log string; who did an action
hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java