I answered the questions reasonably well. One day later they hired me as the Java back-end developer.
For them their team is in a Java world. Their process is Java. The back-end is programmed in Java. The system is built using Java. The dependencies are install via Java. They think and plan in Java.
A purchase order is failing. The service is yielding a 500 error in the shopping card. They could have many Java programmers who can fix this error, but they don't understand why the front-end is sending the wrong JSON in the request.