Updating the Customer Request Type does not fire an Issue Event

Scenario

1. Create an issue in JIRA directly, but don't fill in a Customer Request Type
2. Edit the issue and update the Customer Request Type

Expected behaviour

In step 2 an Issue Event with event type id 2 (update) should be fired.

Actual behaviour

No event is fired.
This means that plugins do not have a way to respond to changes made to the 'Customer Request Type' field.