I've found the solution. There was a line missing on line 289 (ish)
DataSink dataSink = Manager.createDataSink(dataSource, mediaLocator);
/*this line*/ dataSink.addDataSinkListener(this);
dataSink.open();
That allows the application to listen for the end of the file. I've
added it and checked it in to the project and released it as recording-
converter-r1.1.jar
The application now stops when the file has been converted.
Thanks for posting this bug