For the last few months, the Implement Abstract Methods hint has generated "return null;" inside methods whose return type is "void".  I thought this was an obvious bug that would be fixed quickly, but it appears it has not.

To reproduce:

Define an interface
public interface Foo {
   void foo();
}

and an implementation

public class FooImpl implements Foo {
}

Accept the hint on the class declaration line and you get

public class FooImpl implements Foo {
    public void foo() {
      return null;
    }
}

which is completely unusable. How much do you trust the IDE if you have to fix many such methods?  A // TODO comment would make sense;  a throw UnsupportedOperationException() is ugly but would make sense;  the current behavior is 100% guaranteed to be wrong for everybody.