Question about calling constructors of inner classes across different packages

Here's my scenario: I have an interface, a class with an inner class
that implements the interface, and a second class that extends the
first class (and the inner class as well, since I've made it
protected.) The interface, base class, and derived class are all in
separate packages.

Here are my interfaces and classes: Interface I, base class A, inner
class AI (extends interface I), derived class B:

-------------------------------------------------------------------------------------
package testbed.subpacka;

public interface I {
    void f();
}

--------------------------------------------------------------------------------------
package testbed.subpackb;

import testbed.subpacka.*;

public class A {

    protected class AI implements I {
        public AI() { // Remove public and B (below) won't compile
            System.out.println("AI constructed");
        }
        public void f() {
            System.out.println("AI.f()");
        }
    }
}
-----------------------------------------------------------------------------------
package innerclasses;

import testbed.subpacka.*;
import testbed.subpackb.*;

public class B extends A { // Inner class AI and function f()
inherited from A

    public I g() {
        return new AI();
    }
    public static void main(String[] args) {
        B b= new B();
        I t = b.g();
        t.f();
    }
}

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Again, note the different packages, as that's what leads to the issue
at hand:

My problem lies with the B.g() method. Unless I make a AI's
constructor public, B can't return a new AI() in the g() method. I
don't want to make AI's constructor public if I can avoid it.

It seems odd that a class can inherit a protected inner class from a
base class, yet be unable to create a new instance of the inner class
unless the constructor is public, merely because the base and derived
classes are in different packages. Is there a simple way around this
problem?

Thanks for any feedback -