Turn on many more Eclipse warnings, and fix them

- Warn on empty statements, e.g. "for (;;);". These may be
   typos and are easily replaced by "for (;;) {}" which is more
   explicit.
 - Warn on field hiding. This allows cleanup of many acceptance test
   members, at the cost of a couple of renames and the occasional
   suppression (when the field is in a public nested enum that shadows
   a public constant).
 - Warn on unnecessary casts.
 - Warn on unused declared thrown exceptions. In addition to reducing
   method signature length and number of imports, this also eliminated
   some impossible catch blocks.
 - Warn on missing @Override annotations.
 - Warn on unused parameters. This is likely the most controversial,
   as a few relatively common patterns require unused parameters in a
   way that Eclipse can't ignore. However, it also resulted in cleanup
   of a lot of unnecessary injections and method parameters, so I
   think the cost was worth it.

Change-Id: I7224be8b1c798613a127c88507e8cce400679e5d

gerrit-gwtui/src/main/java/com/google/gerrit/client/Dispatcher.java

@@ -240,7 +240,7 @@ public class Dispatcher {
       if (defaultScreenToken != null && !MINE.equals(defaultScreenToken)) {
         select(defaultScreenToken);
       } else {
-        Gerrit.display(token, mine(token));
+        Gerrit.display(token, mine());
       }
 
     } else if (matchPrefix("/dashboard/", token)) {
@@ -433,7 +433,7 @@ public class Dispatcher {
     Gerrit.display(token, screen);
   }
 
-  private static Screen mine(final String token) {
+  private static Screen mine() {
     if (Gerrit.isSignedIn()) {
       return new AccountDashboardScreen(Gerrit.getUserAccount().getId());
 
@@ -644,6 +644,7 @@ public class Dispatcher {
   private static void publish(final PatchSet.Id ps) {
     String token = toPublish(ps);
     new AsyncSplit(token) {
+      @Override
       public void onSuccess() {
         Gerrit.display(token, select());
       }
@@ -670,6 +671,7 @@ public class Dispatcher {
         Gerrit.getPatchScreenTopView() : topView;
 
     GWT.runAsync(new AsyncSplit(token) {
+      @Override
       public void onSuccess() {
         Gerrit.display(token, select());
       }
@@ -743,6 +745,7 @@ public class Dispatcher {
 
   private static void settings(String token) {
     GWT.runAsync(new AsyncSplit(token) {
+      @Override
       public void onSuccess() {
         Gerrit.display(token, select());
       }
@@ -810,6 +813,7 @@ public class Dispatcher {
 
   private static void admin(String token) {
     GWT.runAsync(new AsyncSplit(token) {
+      @Override
       public void onSuccess() {
         if (matchExact(ADMIN_GROUPS, token)
             || matchExact("/admin/groups", token)) {
@@ -983,6 +987,7 @@ public class Dispatcher {
       this.token = token;
     }
 
+    @Override
     public final void onFailure(Throwable reason) {
       if (!isReloadUi
           && "HTTP download failed with status 404".equals(reason.getMessage())) {
@@ -999,6 +1004,7 @@ public class Dispatcher {
 
   private static void docSearch(final String token) {
     GWT.runAsync(new AsyncSplit(token) {
+      @Override
       public void onSuccess() {
         Gerrit.display(token, new DocScreen(skip(token)));
       }