code: public function getReviewContentForm($id)
      {
          $page = $this->findRecord(['ID' => $id]);
          $user = Security::getCurrentUser();
          if (!$page->canEdit() || ($page->hasMethod('canBeReviewedBy') && !$page->canBeReviewedBy($user))) {
              $this->owner->httpError(403, _t(
                  __CLASS__.'.ErrorItemPermissionDenied',
                  'It seems you don\'t have the necessary permissions to review this content'
              ));
              return null;
          }
  
          $form = $this->getReviewContentHandler()->Form($page);
          $form->setValidationResponseCallback(function (ValidationResult $errors) use ($form, $id) {
              $schemaId = $this->owner->join_links($this->owner->Link('schema/ReviewContentForm'), $id);
              return $this->getSchemaResponse($schemaId, $form, $errors);
          });
  
          return $form;
      }
docs: Return a handler for "content due for review" forms, according to the given object ID
  
  @param  int $id
  @return Form|null