title: GAE + GWT Servlet without authentication
body: <p>I'm developing a web application using Google App Engine and GWT.
  I'm using the provided authentication with Google Accounts, so my web.xml contains these lines:</p>
  
  <pre><code>&lt;security-constraint&gt;
      &lt;web-resource-collection&gt;
          &lt;url-pattern&gt;/*&lt;/url-pattern&gt;
      &lt;/web-resource-collection&gt;
      &lt;auth-constraint&gt;
          &lt;role-name&gt;*&lt;/role-name&gt;
      &lt;/auth-constraint&gt;
  &lt;/security-constraint&gt;
  </code></pre>
  
  <p>I need a particular servlet to be free from Google Authentication, because it will be called by Android devices. Please do not suggest a way to authenticate the device because it will not suit my needs.</p>
  
  <p>How can I set up my project so that everything is secured under authentication and just one servlet is not?</p>