code: public void setLoggerLevel(String level) {
          if ("TRACE".equalsIgnoreCase(level)) {
              this.level = TRACE;
          } else if ("DEBUG".equalsIgnoreCase(level)) {
              this.level = DEBUG;
          } else if ("INFO".equalsIgnoreCase(level)) {
              this.level = INFO;
          } else if ("WARN".equalsIgnoreCase(level)) {
              this.level = WARN;
          } else if ("ERROR".equalsIgnoreCase(level)) {
              this.level = ERROR;
          }
      }
docs: httl.properties: logger.level=DEBUG