test.py
-------
import Test

class TargetClass(object):
  def _getattribute(self):
    return self.__attribute
  def _setattribute(self, value):
    self.__attribute = value
  attribute = property(_getattribute, _setattribute)

target = TargetClass()
test = Test(target=target)
test.value = ('bleh', 'blah')
print target.attribute


Test.java
---------
import org.python.core.PyObject;

public class Test {
   public PyObject target;

   public void setValue(PyObject value) {
     target.__setattr__("attribute", value);
   }
}