| Name | Description | Type | Package | Framework |
| Callback | Interface | apache.hedwig.util | Apache BookKeeper | |
| CallbackUtils | Class | apache.hedwig.util | Apache BookKeeper | |
| ConcurrencyUtils | Class | apache.hedwig.util | Apache BookKeeper | |
| Either | Class | apache.hedwig.util | Apache BookKeeper | |
| FileUtils | Class | apache.hedwig.util | Apache BookKeeper | |
| HedwigSocketAddress | This is a data wrapper class that is basically an InetSocketAddress with one extra piece of information for the SSL port (optional). | Class | apache.hedwig.util | Apache BookKeeper |
| Option | Class | apache.hedwig.util | Apache BookKeeper | |
| Pair | Class | apache.hedwig.util | Apache BookKeeper | |
| PathUtils | Class | apache.hedwig.util | Apache BookKeeper | |
| SubscriptionListener | This class is used for subscriber to listen on subscription event. | Interface | apache.hedwig.util | Apache BookKeeper |
| VarArgs | Class | apache.hedwig.util | Apache BookKeeper | |