Jython code stopped working after upgrade from 2.7.1 to 2.7.2

Question

// MyPythonObject.java

import org.python.core.PyObject;
import org.python.expose.ExposedClassMethod;
import org.python.expose.ExposedType;

@ExposedType
public class MyPythonObject extends PyObject {

    @ExposedClassMethod
    public void hello() {
        System.out.println("Hello");
    }
}

// Main.java

import org.python.core.PyStringMap;
import org.python.util.PythonInterpreter;

public class Main {
    public static void main(String[] args) throws Exception {
        PythonInterpreter.initialize(null, null, new String[0]);
        PyStringMap map = new PyStringMap();
        PythonInterpreter pythonInterpreter = new PythonInterpreter(map);
        map.__setitem__("myobj", new MyPythonObject());
        pythonInterpreter.exec("myobj.hello()");
    }
}

The code runs fine on Jython 2.7.1 but fails on Jython 2.7.2:

Exception in thread "main" Traceback (most recent call last):
  File "<string>", line 1, in <module>
AttributeError: 'null' object has no attribute 'hello'

Is this a bug in Jython 2.7.2?

P.S. I asked the same question on GitHub but didn't get any answer yet.

Answer 1

david.perez has asked the right question. The exposer annotations are used to create built-in Python objects in the interpreter. They add code to methods when processed during the Jython build, in classes that will act like a Python built-in.

You do not need them simply to use a class defined in Java from a program written in Python. Take them off and your code works.

I don't know what changed from 2.7.1 to move exposer annotations from unnecessary to harmful. (ASM update, maybe.)