@CommandLine.Option(
      names = {"--logging", "-l"},
      paramLabel = "<LOG VERBOSITY LEVEL>",
      description = "Logging verbosity levels: OFF, ERROR, WARN, INFO, DEBUG, TRACE, ALL")
  public void setLogLevel(final String logLevel) {
    if ("FATAL".equalsIgnoreCase(logLevel)) {
      System.out.println("FATAL level is deprecated");
      this.logLevel = "ERROR";
    } else if (ACCEPTED_VALUES.contains(logLevel.toUpperCase(Locale.ROOT))) {
      this.logLevel = logLevel.toUpperCase(Locale.ROOT);
    } else {
      throw new CommandLine.ParameterException(
          spec.commandLine(), "Unknown logging value: " + logLevel);
    }
  }
Sets log level.

@param logLevel the log level
app/src/main/java/org/hyperledger/besu/cli/options/LoggingLevelOption.java