It seems that Kent is having issues getting Jython to work with the Spring framework. He says:
One of the limitations of Jython is that it doesn't play very well with Java introspection. If you want your Jython methods to be visible to Java introspection you have two choices:
compile your scripts with jythonc
implement a Java interface containing the methods of interest
The first option is problematic (I have had too much trouble with jythonc).
The jythonc that he is referring to I think is the decorator language you can use in a jython class definition that forces jythonc to generate a specific java class with the function signature you want. For Example: