code: public void setOptMLower(boolean optMLower) {
      checkCanSetRenameOption("-m");
      if (optMLower && optMUpper) {
        throw new IllegalArgumentException(ExceptionMessageMap.getMessage("000120")
            + "  -m cannot be used with -M.");
      } 
      this.optMLower = optMLower;
    }
docs: Checks whether the -m option should be set and sets it.
  
  @param optMLower True if the -m option should be used, false otherwise.