WW-2537 Fix generics in all codebase

Starting with Java5 enhancements in S2. 
This patch applies required changes to S2 related to the "generified xwork"

XWork Java5 enhancements 
o added generics where possible
o use parameterizes Collection classes where possible
o converted for to for-each loops
o optimized imports
o updated tests
o aligned parameter types with Struts2
o fixed some minor bugs

git-svn-id: https://svn.apache.org/repos/asf/struts/struts2/trunk@670170 13f79535-47bb-0310-9956-ffa450edef68

apps/blank/src/test/java/example/ConfigTest.java

@@ -44,7 +44,7 @@ public class ConfigTest extends StrutsTestCase {
                 ActionSupport.INPUT.equals(result));
     }
 
-    protected Map assertFieldErrors(ActionSupport action) throws Exception {
+    protected Map<String, List<String>> assertFieldErrors(ActionSupport action) throws Exception {
         assertTrue(action.hasFieldErrors());
         return action.getFieldErrors();
     }