code: public void setLoggingLevel(final int loggingLevel, final Class<?>... deviceClassNames) {
  
          if (rootLoggingLevel < loggingLevel) {
              setRootLoggingLevel(loggingLevel);
          }
          System.out.println("set logging to " + LoggingLevel.getLevelFromInt(loggingLevel));
          final Logger tangoLogger = LoggerFactory.getLogger("org.tango.server");
          if (tangoLogger instanceof ch.qos.logback.classic.Logger) {
              final ch.qos.logback.classic.Logger logbackLogger = (ch.qos.logback.classic.Logger) tangoLogger;
              logbackLogger.setLevel(LoggingLevel.getLevelFromInt(loggingLevel));
          }
          final Logger blackboxLogger = LoggerFactory.getLogger(Constants.CLIENT_REQUESTS_LOGGER);
          if (blackboxLogger instanceof ch.qos.logback.classic.Logger) {
              final ch.qos.logback.classic.Logger logbackLogger = (ch.qos.logback.classic.Logger) blackboxLogger;
              logbackLogger.setLevel(LoggingLevel.getLevelFromInt(loggingLevel));
          }
          for (int i = 0; i < deviceClassNames.length; i++) {
              final Logger deviceLogger = LoggerFactory.getLogger(deviceClassNames[i]);
              if (deviceLogger instanceof ch.qos.logback.classic.Logger) {
                  final ch.qos.logback.classic.Logger logbackLogger = (ch.qos.logback.classic.Logger) deviceLogger;
                  logbackLogger.setLevel(LoggingLevel.getLevelFromInt(loggingLevel));
              }
          }
  
      }
docs: Set the level of all loggers of JTangoServer
  
  @param loggingLevel