code: protected function renderV2()
      {
          if ('google' == $this->requestSource) {
              $out = [
                  'basicCard' => [
                      'title' => $this->title,
                  ],
                  'platform' => $this->v2PlatformMap[$this->requestSource],
              ];
  
              if ($this->text) {
                  $out['basicCard']['formattedText'] = $this->text;
              }
  
              if ($this->imageUrl) {
                  $out['basicCard']['image'] = [
                      'imageUri'          => $this->imageUrl,
                      'accessibilityText' => 'accessibility text',
                  ];
              }
  
              if ($this->buttons) {
                  $out['basicCard']['buttons'] = [];
                  foreach ($this->buttons as $button) {
                      $out['basicCard']['buttons'][] =
                          [
                              'title'         => $button['buttonText'],
                              'openUriAction' => [
                                  'uri' => $button['buttonUrl'],
                              ],
                          ];
                  }
              }
  
              return $out;
          } else {
              $out = [
                  'card' => [
                      'title' => $this->title,
                  ],
                  'platform' => $this->v2PlatformMap[$this->requestSource],
              ];
  
              if ($this->text) {
                  $out['card']['subtitle'] = $this->text;
              }
  
              if ($this->imageUrl) {
                  $out['card']['imageUri'] = $this->imageUrl;
              }
  
              if ($this->buttons) {
                  $out['card']['buttons'] = [];
                  foreach ($this->buttons as $button) {
                      $out['card']['buttons'][] =
                          [
                              'text'         => $button['buttonText'],
                              'postback' => $button['buttonUrl'],
                          ];
                  }
              }
  
              return $out;
          }
      }
docs: Render response as array for API V2.
  
  @return array