public function addSynonymAction(Request $request, $mainTagId, $languageCode)
    {
        $this->denyAccessUnlessGranted('ez:tags:addsynonym');

        $synonymCreateStruct = $this->tagsService->newSynonymCreateStruct($mainTagId, $languageCode);

        $form = $this->createForm(
            SynonymCreateType::class,
            $synonymCreateStruct,
            [
                'action' => $request->getPathInfo(),
            ]
        );

        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
            $newSynonym = $this->tagsService->addSynonym($form->getData());

            $this->addFlashMessage('success', 'tag_added', ['%tagKeyword%' => $newSynonym->keyword]);

            return $this->redirectToTag($newSynonym);
        }

        return $this->render(
            '@NetgenTags/admin/tag/add.html.twig',
            [
                'form' => $form->createView(),
            ]
        );
    }