code: public static void setLogLevel(String cls, String level){
          Logger l = null;
          if(Objects.isNullOrEmpty(cls))
              l = LogManager.getRootLogger();
          else
              l = LogManager.getLogger(cls);
          if(level.equalsIgnoreCase("TRACE"))
              l.setLevel(Level.TRACE);
          else if(level.equalsIgnoreCase("DEBUG"))
              l.setLevel(Level.DEBUG);
          else if(level.equalsIgnoreCase("INFO"))
              l.setLevel(Level.INFO);
          else if(level.equalsIgnoreCase("WARN"))
              l.setLevel(Level.WARN);
          else if(level.equalsIgnoreCase("ERROR"))
              l.setLevel(Level.ERROR);
      }
docs: Set log level
  
  @param cls if null, then rootLogger
  @param level one of ['TRACE','DEBUG','INFO','WARN','ERROR']