ConnectionList addBackup(QueueConnectionImpl queueConnection) {
      ArrayList<Connection> newBackups = new ArrayList<>(backups);
      newBackups.add(queueConnection);
      return new ConnectionList(primary, newBackups, primaryDiscoveryException, failedPrimary);
    }
The primaryDiscoveryException flag is stronger than just not having any queue connections It
also means we tried all of the possible queue servers and we'ren't able to connect.
geode-core/src/main/java/org/apache/geode/cache/client/internal/QueueManagerImpl.java