Add Slideshow to Cover

[sadiefp]

I told my boss that we cannot add a slideshow to the cover of an Instant Article, based on the documentation I found online & the cover type enforcement in the SDK. Based on these sources, images & video are the only allowable covers.

https://developers.facebook.com/docs/instant-articles/guides/articlecreate#specify-cover
https://developers.facebook.com/docs/instant-articles/reference/cover#options
https://github.com/facebook/facebook-instant-articles-sdk-php/blob/master/src/Facebook/InstantArticles/Elements/Header.php#L103

But he found instant articles with slideshows as covers on Wired.
Wired's code:
https://github.com/whyisjake/Simple-Instant-Articles-for-Facebook/blob/db9651d2c9925b4fb0cced0861fb684fa0528bcd/templates/article-cover.php
An example Wired post with a slideshow cover:
https://www.facebook.com/wired/posts/10153790809838721

If I manually update an instant article, moving the slideshow figure into the header, facebook doesn't throw any errors. Playing with the SDK locally, if I add Slideshow to the allowable types for the cover, the slideshow is added with no issue to the header. If Slideshow's aren't allowed in the header, why don't I get any errors when I manually add them? Is this a fault on Facebook's documentation? Is a slideshow basically an image?

Steps required to reproduce the problem

1. Try to add a slideshow as a cover:

$instant_article->getHeader()->withCover($slideshow);

Expected Result

• Slideshow added to the <header>.

    <article>
      <header>
        <figure class="op-slideshow">
          <figure>
            <img src="http://example.com/image1.jpg"/>
            <figcaption>Caption caption caption...</figcaption>
          </figure>
          [...]
      </figure>
      <h1>Example Title</h1>
      [...]         
     </header>
     [...]
  </article>

Actual Result

• Error

Additional uncaught exception thrown while handling exception.

InvalidArgumentException: Method expects this value ----[ object(Facebook\InstantArticles\Elements\Slideshow)#587 (5) { [...] } ]---- to be one of the types ====[ array(2) { 
[0]=> string(39) "Facebook\InstantArticles\Elements\Image"
 [1]=>string(39) "Facebook\InstantArticles\Elements\Video" 
} ]==== in Facebook\InstantArticles\Validators\Type::throwException() (line 182 of /var/www/drupalvm/sites/all/vendor/facebook/facebook-instant-articles-sdk-php/src/Facebook/InstantArticles/Validators/Type.php).

[everton-rosario]

@sadiefp Can you check if it fixes your issue?

[sadiefp]

It worked for me.

Thanks for the quick response!