docs: @Subscribe
      public void undispatched(DeadEvent e) {
          if (!m_done.get() && e.getEvent() instanceof ImporterChannelAssignment) {
              ImporterChannelAssignment assignment = (ImporterChannelAssignment)e.getEvent();
  
              synchronized (m_undispatched) {
                  NavigableSet<String> registered = m_callbacks.getReference().navigableKeySet();
                  NavigableSet<String> unregistered = m_unregistered.getReference();
                  if (registered.contains(assignment.getImporter())) {
                      m_eb.post(assignment);
                  } else if (!assignment.getAdded().isEmpty()
                          && unregistered.contains(assignment.getImporter())) {
                      LOG.warn("(" + m_hostId
                              + ") disgarding assignment to unregistered importer "
                              + assignment);
                  } else {
                      m_undispatched.add(assignment);
                  }
              }
          }
      }