Impact: adding a @Ghost to an external spec breaks correct programs, unless every constructor sets the ghost. The error names a ghost called old, which is internal and not in the spec.

Minimal reproducer (an external spec and a client, in one directory)

// EditRefinements.java
@ExternalRefinementsFor("javax.swing.undo.AbstractUndoableEdit")
@StateSet({"done", "undone"})
@Ghost("int supported")
public interface EditRefinements {
    @StateRefinement(to = "done(this)")
    void AbstractUndoableEdit();

    @StateRefinement(from = "done(this)")
    boolean canUndo();
}

// Client.java
public class Client {
    public static void main(String[] args) {
        AbstractUndoableEdit e = new AbstractUndoableEdit();
        e.canUndo();
    }
}

Expected: Correct! Passed Verification.

Actual (main @ f7f366c, and 1a506fe):

Not Found Error: Ghost 'old' could not be found

The same shape written in-source (an annotated class with the same @Ghost) verifies. So does the external spec when the constructor's to also sets the ghost: to = "done(this) && supported(this) == 0".

Real-world scenario. I was writing a spec for javax.management.modelmbean.RequiredModelMBean with a ghost to refuse load()/store(), which always throw; from = "false" doesn't work (#449). With the ghost unset, every correct call such as m.setModelMBeanInfo(info) failed with this error.