A DESCRIPTION OF THE REQUEST :
When a subtype restricts the bounds of a type variable of its supertype, any inherited methods with a return type of that variable should have a bridge method created. Currently, moving such a method from the derived to base type will cause binary incompatibility.

Care needs to be exercised for protected methods inherited across packages.

JUSTIFICATION :
It should be possible to move such methods to super types, without binary incompatibility.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
$ /usr/java/jdk1.6.0/bin/javap Derived
Compiled from "Derived.java"
public class Derived extends Base{
    public Derived();
    Derived getThis();
    Base getThis();
    public Derived function();
}
ACTUAL -
$ /usr/java/jdk1.6.0/bin/javap Derived
Compiled from "Derived.java"
public class Derived extends Base{
    public Derived();
    Derived getThis();
    Base getThis();
}

with 1.5.0_04:

C:\>javac Derived.java

C:\>javap Derived
Compiled from "Derived.java"
public class Derived extends Base{
    public Derived();
    Derived getThis();
    Base getThis();
}


---------- BEGIN SOURCE ----------
abstract class Base<THIS extends Base> {
    abstract THIS getThis();
    public THIS function() {
         return getThis();
    }
}
public class Derived extends Base<Derived> {
    Derived getThis() {
        return this;
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Override all methods with this problem.