Remove unnecessary suppression of "unchecked"

Eclipse reports a warning that this suppression is not necessary.

This reverts commit 01675359e0.

Change-Id: I54f4b30c68ddeba96a0dd2206d5e08cc881547f6

gerrit-server/src/main/java/com/google/gerrit/server/cache/ForwardingRemovalListener.java

@@ -52,7 +52,6 @@ public class ForwardingRemovalListener<K, V> implements RemovalListener<K, V> {
     }
   }
 
-  @SuppressWarnings("unchecked")
   public void onRemoval(RemovalNotification<K, V> notification) {
     for (CacheRemovalListener<K, V> l : listeners) {
       l.onRemoval(pluginName, cacheName, notification);