I have

package P

protected class A implements B {
    blabla...
}

public interface B {
public void bongo();
}

And then I do the things below outside of package P

B a = somehowGetAHandleOfAnInstanceOfA

Method m = a.getClass().getMethod("bongo", new Class[] {Void.class});

When I do

m.invoke(a, null);

I get a IllegalAccessException.

At least the docs should point out this behavior (so it's at least a docu bug).
I don't know if the behavior is not a bug.
getMethod should work for all methods that A understands.
After all I can do a.bongo(), and reflection should support
everything that can be done directly.

The workaround is

a.getInterfaces() and then look in the interfaces for the right Method instance.