/*
   * Set the authentication method
   * Value must be one of:
   *   +Openwsman::NO_AUTH_STR+
   *   +Openwsman::BASIC_AUTH_STR+
   *   +Openwsman::DIGEST_AUTH_STR+
   *   +Openwsman::PASS_AUTH_STR+
   *   +Openwsman::NTLM_AUTH_STR+
   *   +Openwsman::GSSNEGOTIATE_AUTH_STR+
   */
  void set_auth_method(const char *am) {