title: Is a trailing ampersand legal in a URL?
body: <p>A URL like</p>
  <pre><code>http://localhost/path?a=b&amp;c=d
  </code></pre>
  <p>is fine - but what is the status of the same URL with a trailing ampersand?</p>
  <pre><code>http://localhost/path?a=b&amp;c=d&amp;
  </code></pre>
  <p>For example the Java Servlet API allows it where <a href="https://github.com/spray/spray/wiki" rel="nofollow noreferrer">Scala's Spray</a> does not (ie it throws an error).</p>
  <p>I've tried to find the answer in the <a href="https://www.rfc-editor.org/rfc/rfc3986" rel="nofollow noreferrer">URI syntax spec</a>, but not sure how to parse their grammar.</p>