code: private void setAndValidateProperties(String cfgAuthentication,
                                            String cfgAuthorization,
                                            String cfgUserRegistry) {
          if ((cfgAuthentication == null) || cfgAuthentication.isEmpty()) {
              throwIllegalArgumentExceptionMissingAttribute(CFG_KEY_AUTHENTICATION_REF);
          }
          this.cfgAuthenticationRef = cfgAuthentication;
  
          if ((cfgAuthorization == null) || cfgAuthorization.isEmpty()) {
              throwIllegalArgumentExceptionMissingAttribute(CFG_KEY_AUTHORIZATION_REF);
          }
          this.cfgAuthorizationRef = cfgAuthorization;
  
          if ((cfgUserRegistry == null) || cfgUserRegistry.isEmpty()) {
              throwIllegalArgumentExceptionMissingAttribute(CFG_KEY_USERREGISTRY_REF);
          }
          this.cfgUserRegistryRef = cfgUserRegistry;
      }
docs: Sets and validates the configuration properties. If any of the
  configuration properties are not set, an IllegalArgumentException
  is thrown.
  
  @param cfgAuthentication
  @param cfgAuthorization
  @param cfgUserRegistry
  @throws IllegalArgumentException if any of the configuration elements
  are not set