code: protected Tag getControllerTag(Class<? extends Controller> controllerClass) {
          if (controllerClass.isAnnotationPresent(ApiOperations.class)) {
              ApiOperations annotation = controllerClass.getAnnotation(ApiOperations.class);
              io.swagger.models.Tag tag = new io.swagger.models.Tag();
              tag.setName(Optional.fromNullable(Strings.emptyToNull(annotation.tag())).or(controllerClass.getSimpleName()));
              tag.setDescription(translate(annotation.descriptionKey(), annotation.description()));
  
              if (!Strings.isNullOrEmpty(annotation.externalDocs())) {
                  ExternalDocs docs = new ExternalDocs();
                  docs.setUrl(annotation.externalDocs());
                  tag.setExternalDocs(docs);
              }
  
              if (!Strings.isNullOrEmpty(tag.getDescription())) {
                  return tag;
              }
          }
          return null;
      }
docs: Returns the Tag for a controller.
  
  @param controllerClass
  @return a controller tag or null