adding error diagnostics as to where servlet API is loaded from.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@5706 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/WebAppMain.java

@@ -75,7 +75,7 @@ public class WebAppMain implements ServletContextListener {
             try {
                 ServletResponse.class.getMethod("setCharacterEncoding",String.class);
             } catch (NoSuchMethodException e) {
-                context.setAttribute(APP,new IncompatibleServletVersionDetected());
+                context.setAttribute(APP,new IncompatibleServletVersionDetected(ServletResponse.class));
                 return;
             }