Execute and Wait Interceptor

There should be closing "/" for </interceptor-ref> and </param> in these examples.

The "Extending the Interceptor" needs an additional note.

If you are extending BackgroundProcess and have any initialization in your constructor after the call to the superclass's constructor, beware that there may be a race condition: the parent constructor calls start() on the thread before returning, and therefore beforeInvocation might be called before your extra initialization is complete. Make sure you add in synchronization logic that makes beforeInvocation wait until the full constructor is complete before it does it's thing.