code: public function getUrl($context, array $extras = [], $value = ''): string
      {
          $providers = (isset($extras['providers']) && \is_array($extras['providers'])) ? $extras['providers'] : null;
  
          if (!$this->supportsContext($context, $providers)) {
              return '';
          }
  
          return $this->router->generate('contao_backend_picker', compact('context', 'extras', 'value'));
      }
docs: {@inheritdoc}