in invoker/core/src/main/java/com/google/cloud/functions/invoker/GcfEvents.java [253:262]
SourceAndSubject convertResourceToSourceAndSubject(String resourceName, Event legacyEvent) {
Matcher matcher = FIREBASE_DB_RESOURCE_PATTERN.matcher(resourceName);
String location = parseLocation(legacyEvent);
if (matcher.matches() && location != null) {
String resource = String.format("projects/_/locations/%s/%s", location, matcher.group(1));
String subject = matcher.group(2);
return SourceAndSubject.of(resource, subject);
}
return super.convertResourceToSourceAndSubject(resourceName, legacyEvent);
}