@Test
    public void testBlockInConnectorStart() throws Exception {
        log.info("Starting test testBlockInConnectorStart");
        createConnectorWithBlock(BlockingConnector.class, CONNECTOR_START);
        Block.waitForBlock();

        createNormalConnector();
        verifyNormalConnector();

        // Try to restart the connector
        assertRequestTimesOut(
                "restart connector that blocks during start",
                () -> connect.restartConnector(BLOCKING_CONNECTOR_NAME),
                "The worker is currently starting the connector"
        );
    }
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