From this Oracle Java tutorial:
The WildcardError example produces a capture error when compiled:
public class WildcardE
List> does mean list of object of unknown type, it's not the same as List.
Because we don't know the type of elements in the list result of i.get(0) is considered by Java as Object, and you cannot add Object to List>. In case as your Java could be smarter, but in more complex code with > wildcards it's easy to make it no type safe.