title: How to escape forward slash in the matches constraint
body: <p>How can I escape the forward slashes in the regex when using the matches constraint? This is what I tried:</p>
  
  <pre><code>constraints {
      url (
          matches: "^http://www.google.com/$"
      )
  }
  </code></pre>
  
  <p>Error: <code>solution: either escape a literal dollar sign "\$5" or bracket the value expression "${5}"</code></p>
  
  <pre><code>constraints {
      url (
          matches: "^http:\/\/www.google.com\/$"
      )
  }
  </code></pre>
  
  <p>Error: <code>unexpected char: '\'</code></p>