A DESCRIPTION OF THE REQUEST :
Legacy collections which support clone (Vector/Hashtable/Stack), have specified the return type of clone as Object. This presents problems, because it causes "unchecked" warnings.

For example:

Vector<String> v = ...;
Vector<String> copy = (Vector<String>) v.clone();

results in an "unchecked" warning.


JUSTIFICATION :
The change is minimal. For example, for Vector, it's simply a matter of replacing "Object" with "Vector<E>" in the source code.

There are some workarounds, but none of them are satisfactory:
1) add @SuppressWarnings("unchecked")
=> this needlessly clutters the source code
2) use copy constructors (e.g. "new Vector<String>(v)") instead
=> unlike the clone method, using copy constructors isn't thread-safe
3) replace the usage of legacy collections with modern alternatives
=> again, the problem is that Vector and Hashtable are thread-safe, while typical collections like ArrayList and HashMap aren't. So it's not always easy or even possible to do so


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The clone() method:
- in Vector must return Vector<E>
- in Hashtable must return HashTable<K, V>
- in Stack must be added & return Stack<E>

ACTUAL -
The clone() methods return Object, which requires casts, which results in compiler warnings.