@Override
    public boolean cleanupRecoverableState(ResumeRecoverable resumable) {
        // we can't safely clean up any state prior to commit, so do nothing here
        // see discussion: https://github.com/apache/flink/pull/15599#discussion_r623127365
        return true;
    }
@Test
    public void testCleanupRecoverableState() {
        assertTrue(writer.cleanupRecoverableState(resumeRecoverable));
    }