Use CDATA in XML

src/main/java/fr/inrae/agroclim/devcas/ValidateCAS2Servlet.java

@@ -52,7 +52,7 @@ public final class ValidateCAS2Servlet extends HttpServlet {
      * The XML response in case of validation failure.
      */
     private static final String FAILURE_XML = "<cas:serviceResponse xmlns:cas=\"http://www.yale.edu/tp/cas\">%n"
-            + " <cas:authenticationFailure code=\"%s\">%s</cas:authenticationFailure>%n" //
+            + " <cas:authenticationFailure code=\"%s\"><![CDATA[%s]]></cas:authenticationFailure>%n" //
             + "</cas:serviceResponse>";
 
     /**