Exposes implementation information to the caller?

Question

Within JLS Capture Conversion it discusses two ways to write the signature of the reverse method:

1. public static void reverse(List<?> list);

2. public static <T> void reverse(List<T> list);

   My question is why the second exposes implementation information to the caller ? Specifically within the example it says that the second is undesirable, as it exposes implementation information to the caller.

Answer 1

List<?> will return elements of type Object when iterating through the lyst. (eg: lyst.get(..) )

List<T> will return elements of Type T.

This helps to hide unneeded information to those implementing / using the interfaces.