docs: @Override
      public void validate(ValidationHelper helper, Context context, String key, ExternalDocumentation t) {
          ValidatorUtils.validateRequiredField(t.getUrl(), context, "url").ifPresent(helper::addValidationEvent);
  
          if (t.getUrl() != null) {
              if (!ValidatorUtils.isValidURI(t.getUrl())) {
                  final String message = Tr.formatMessage(tc, "externalDocumentationInvalidURL", t.getUrl());
                  helper.addValidationEvent(new ValidationEvent(ValidationEvent.Severity.ERROR, context.getLocation("url"), message));
              }
          }
      }