anchor.diff:          Lijst met roles:
           <ol>
               <c:if test="${pageContext.request.userPrincipal != null}" >
  -                <c:forEach var="r" items="${pageContext.request.userPrincipal.groups}">
  -                    <li><c:out value="${r.name}"/></li>
  -                </c:forEach>
  +                <c:catch>
  +                    <c:forEach var="r" items="${pageContext.request.userPrincipal.groups}">
  +                        <li><c:out value="${r.name}"/></li>
  +                    </c:forEach>
  +                </c:catch>
  +                <c:catch>
  +                    <c:forEach var="r" items="${pageContext.request.userPrincipal.roles}">
  +                        <li><c:out value="${r}"/></li>
  +                    </c:forEach>
  +                </c:catch>
               </c:if>
           </ol>
           <p>
           Test HttpServletRequest.isUserInRole():
           <p>
           <c:if test="${!empty param.role}">
  -            Rol <b><c:out value="${param.role}"/>: <b><%= request.isUserInRole(request.getParameter("role")) %></b>
  +            Rol <b><c:out value="${param.role}"/>: <%= request.isUserInRole(request.getParameter("role")) %></b>
               <p>
           </c:if>
           <form action="${pageContext.request.pathInfo}" method="get">
  
positive.code: <html>
      <head>
          <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
          <meta http-equiv="refresh" content="2">
          <title>Autorisatie info</title>
      </head>
      <body>
  
negative.code:                 document.forms[0].role.focus();
              }
          </script>
  
          <p>Headers:</p>
          <c:catch>
              <table style="font-family: monospace">
                  <c:forEach var="h" items="${header}">
                      <tr><td><c:out value="${h.key}"/></td><td><c:out value="${h.value}"/></td></tr>
                  </c:forEach>
              </table>
          </c:catch>   
  
          <p>Request attributes: </p>
          <table style="font-family: monospace">
              <c:forEach var="a" items="${requestScope}">
                  <tr><td><c:out value="${a.key}"/></td><td><c:out value="${a.value}"/></td></tr>
              </c:forEach>
          </table>
  
          <p>Page context: </p>
          <table style="font-family: monospace">
              <c:forEach var="a" items="${pageScope}">
                  <tr><td><c:out value="${a.key}"/></td><td><c:out value="${a.value}"/></td></tr>
              </c:forEach>
          </table>
      </body>
  </html>
  