@Override
            public boolean isCancelled() {
                return workerGetFuture.isCancelled()
                        || connectorGetFuture.isCancelled();
            }
Get the offset values for the specified keys.

<p>If configured to use a connector-specific offset store, priority is given to the values contained in that store,
and the values in the worker-global offset store (if one is provided) are used as a fallback for keys that are not
present in the connector-specific store.

<p>If not configured to use a connector-specific offset store, only the values contained in the worker-global
offset store are returned.
@param keys list of keys to look up
@return future for the resulting map from key to value
connect/runtime/src/main/java/org/apache/kafka/connect/storage/ConnectorOffsetBackingStore.java