Jython library for interfaces

Question

I'm working through this Jython guide to make a one-to-one Jython Object Factory.

The writer speaks of a org.jython.book.interfaces that he uses through out the tutorial.

In order to utilize a Jython module using this technique, you must either ensure that the .py module is contained within your sys.path, or hard code the path to the module within your Java code. A python module that implements a Java interface to create a building object

from org.jython.book.interfaces import BuildingType

I've imported every jython.jar I could find, and this part of the library does not exist. In his tutorial, he creates a building.py, buildingType.java, and a buildingFactory.java.

Here is my code where the app hits and fails to keep running:

package my.irondb_datdiff;


import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.util.PythonInterpreter;


public class DiffFactory {

  private PyObject diffClass;

  public DiffFactory() {
    PythonInterpreter pyin = new PythonInterpreter();

    pyin.exec("from make_diff_from_irons import make_diff_from_irons");
    diffClass = pyin.get("make_diff_from_irons");        

}

  public make_Diff run(String export, String source, String target) {

    PyObject diffObject = diffClass.__call__(
        new PyString(export),
        new PyString(source),
        new PyString(target));

    return (make_Diff)diffObject.__tojava__(make_Diff.class);

}

}

And here is the line it hits that it files on after doing "run":

from my.irondb_datdiff import make_Diff

I've made my versions of these, but I get the error that my module does not exist. I'm sure this is because I'm not importing the interface because I can't find the right module in the library.

Any thoughts?

(Also I realize a another poster had a similar question about this exact step in the tutorial, but this question is different and the other posters answer didn't answer my question. So please don't mark as duplicate.)