Twitter preview not available

[avdata99]

Previews for Twitter are not working

I didn't found a plugin for this or code like this in this theme

<meta name="twitter:card" value="summary" />
<meta name="twitter:url" value="" />
<meta name="twitter:title" value="" />
<meta name="twitter:description" value="" />
<meta name="twitter:image" value="" />
<meta name="twitter:site" value="" />
<meta name="twitter:creator" value="" />