private void expectTaskGetTopic() {
        when(statusBackingStore.getTopic(any(), eq(TOPIC)))
                .thenAnswer(invocation -> new TopicStatus(
                        invocation.getArgument(1),
                        new ConnectorTaskId(invocation.getArgument(0), 0),
                        time.milliseconds()
                ));
    }
@return how many times an {@link OffsetStorageWriter#doFlush(Callback) offset flush} took place
connect/runtime/src/test/java/org/apache/kafka/connect/runtime/ExactlyOnceWorkerSourceTaskTest.java