private void verifyPossibleTopicCreation() {
        if (enableTopicCreation) {
            verify(admin).createOrFindTopics(any());
        } else {
            verify(admin, never()).createOrFindTopics(any());
        }
    }
@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