=act #16330 deprecating akka.util.Crypt

 * Fix for #16330 
 * Additionally clean several files up: final modifiers on objects and final class members, unused imports, iterators.nonEmpty instead of !iterators.isEmpty
I reviewed nonEmpty implementation and
scala.collection.TraversableOnce#nonEmpty
```scala
def nonEmpty: Boolean = !isEmpty
```
So it is really the same as `!iterators.isEmpty`. Or did I misunderstand you? Anyway I can roll all back if you insist