How should I declare an instance of an inner class of classes that implement the same interface

I have the following structure

public interface I{...}

public class A implements I{
  ....

  public static class Inside{
    ...
    //data from here are used in A. Therefore tight coupling.
  }
}

public class B implements I{
  ....

  public static class Inside{
    ...
    //data from here are used in B.  Therefore tight coupling.
  }
}

Note that the implementation of A.Inside is somewhat different from B.Inside. Then I have another class that accesses Inside as

public class AW extends X{
  ...
}

public class BW extends X{
  ...
}

public class X{
  ...
  public Obj doSomeWork(Inside inside){
    mInside = inside;
    ....//some work
  }
}


//UsageB is similar in it's implementation of the B stack
public class UsageA{
  A.AW inst = new AW();
  Inside in = A.Inside();
  inst.doSomeWork(in);
}

question: What should be the type of mInside? I don't want to have two mInside variables.

AW is tailored for A and BW is tailored for B