Updated explanation of a potentially unexpected cast to refer to the JDK bug that necessitates it

apis/ec2/src/main/java/org/jclouds/ec2/compute/strategy/EC2ListNodesStrategy.java

@@ -96,6 +96,7 @@ public class EC2ListNodesStrategy implements ListNodesStrategy {
                   @SuppressWarnings("unchecked")
                   @Override
                   public Future<Set<? extends Reservation<? extends RunningInstance>>> apply(String from) {
+                     // see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7126754
                      return castToSpecificTypedFuture(client.getInstanceServices().describeInstancesInRegion(from));
                   }
 
@@ -104,7 +105,6 @@ public class EC2ListNodesStrategy implements ListNodesStrategy {
       return concat(concat(reservations));
    }
 
-   // "hide" this cast (i.e. do not perform inline) from the Java 7 compiler - see http://stackoverflow.com/questions/8637937/why-does-a-generic-cast-of-a-list-extends-set-to-listset-succeed-on-sun
    @SuppressWarnings("unchecked")
    private static <T> Future<T> castToSpecificTypedFuture(Future<? extends T> input) {
        return (Future<T>) input;