docs: @Override
      public boolean isSet(String propName) {
          if (propName.equals(PROP_PRINCIPAL_NAME)) {
              return isSetPrincipalName();
          }
          if (propName.equals(PROP_PASSWORD)) {
              return isSetPassword();
          }
          if (propName.equals(PROP_REALM)) {
              return isSetRealm();
          }
          if (propName.equals(PROP_CERTIFICATE)) {
              return isSetCertificate();
          }
          return super.isSet(propName);
      }