debugClearEvents method
Empties the ring and the held details, leaving handlers and attachments alone.
For tests. GuestChannels.core is one object for the whole process, so
without this a test reads the events the test before it emitted — which
is exactly how the first feed test failed.
Implementation
@visibleForTesting
void debugClearEvents() {
_ring.clear();
_details.clear();
_detailsBytes = 0;
}