title: auth-constraint element in web.xml
body: <p>Let's say I have 3 sercurity-constrant elements defined in web.xml, everyone pointing to same url-pattern. And I have these 3 auth-constraint element separately defined in each of them:</p>
  
  <pre><code>&lt;security-constraint&gt;
  ...
      &lt;auth-constraint&gt;Role1&lt;/auth-constraint&gt;
  &lt;/security-constraint&gt;
  &lt;security-constraint&gt;
  ...
      &lt;auth-constraint&gt;Role2&lt;/auth-constraint&gt;
  &lt;/security-constraint&gt;
  &lt;security-constraint&gt;
  ...
      &lt;auth-constraint/&gt;
  &lt;/security-constraint&gt;
  </code></pre>
  
  <p>Who can access resource specified in url-pattern? Nobody or Role1 and Role2?</p>