Search Action for Sitelinks Searchbox

Google docs specifies that the target should have {search_term_string} like so:

<script type="application/ld+json">
{
   "@context": "http://schema.org",
   "@type": "WebSite",
   "url": "https://www.example-petstore.com/",
   "potentialAction": {
     "@type": "SearchAction",
     "target": "https://query.example-petstore.com/search?q={search_term_string}",
     "query-input": "required name=search_term_string"
   }
}
</script>

But the plugin seems to output “{search_term}”

The Google Structured Data Tool also complains about the error:

http://schema.org/True
valueName:	missing and required

I think this should be fixed…
thanks.

https://wordpress.org/plugins/wordpress-seo/