Please add this (or equivalent) to the bottom of section 12.1. (Interceptors):
Interceptors are invoked by Hibernate's default event listeners. For example, interceptors' onSave() method is invoked by Hibernate's DefaultSaveOrUpdateEventListener
Please add this (or equivalent) to the bottom of section 12.2 (Event System):
When changing the event listeners be sure to keep the various Hibernate default listeners. These listeners actually perform much of Hibernate's persistence work, including invocation of the interceptors. Without those default listeners, Hibernate will quietly do nothing.