XWIKI-22394: When accessing directly Tomcat, the resolved source URL can contain an extra port

* bulletproofing for tests

(cherry picked from commit 50e1c84c)

xwiki-platform-core/xwiki-platform-container/xwiki-platform-container-servlet/src/main/java/org/xwiki/container/servlet/HttpServletUtils.java

@@ -193,8 +193,9 @@ private static void appendHostPort(HttpServletRequest request, StringBuilder bui
 
         // Ask the application server (we don't start with that because it's very often wrong or badly configured
         // behind an HTTP proxy...)
-        String requestURLString = request.getRequestURL().toString();
-        if (!requestURLString.isEmpty()) {
+        StringBuffer buffer = request.getRequestURL();
+        if (buffer != null && !buffer.isEmpty()) {
+            String requestURLString = buffer.toString();
             try {
                 URL requestURL = new URL(requestURLString);
                 builder.append(requestURL.getHost());