code: void register(String repoFullName) {
      lock.writeLock().lock();
      try {
        if (!entityListenersByRepo.containsKey(requireNonNull(repoFullName))) {
          entityListenersByRepo.put(repoFullName, HashMultimap.create());
        }
      } finally {
        lock.writeLock().unlock();
      }
    }
docs: Register a repository to the entity listeners service once