public static ConfigDef config() {
            return new ConfigDef()
                .define(
                    BLOCK_CONFIG,
                    ConfigDef.Type.STRING,
                    "",
                    ConfigDef.Importance.MEDIUM,
                    "Where to block indefinitely, e.g., 'Connector::start', 'Connector::initialize', " 
                        + "'Connector::taskConfigs', 'Task::version', 'SinkTask::put', 'SourceTask::poll'"
                );
        }
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