@Test
    public void testWorkerRestartWithBlockInConnectorStart() throws Exception {
        log.info("Starting test testWorkerRestartWithBlockInConnectorStart");
        createConnectorWithBlock(BlockingConnector.class, CONNECTOR_START);
        // First instance of the connector should block on startup
        Block.waitForBlock();
        createNormalConnector();
        connect.removeWorker();

        connect.addWorker();
        // After stopping the only worker and restarting it, a new instance of the blocking
        // connector should be created and we can ensure that it blocks again
        Block.waitForBlock();
        verifyNormalConnector();
    }
Tests situations during which certain connector operations, such as start, validation,
configuration and others, take longer than expected.
connect/runtime/src/test/java/org/apache/kafka/connect/integration/BlockingConnectorTest.java