public TaskHandle taskHandle(String taskId, Consumer<SinkRecord> consumer) {
        return taskHandles.computeIfAbsent(taskId, k -> new TaskHandle(this, taskId, consumer));
    }
Get or create a task handle for a given task id. The task need not be created when this method is called. If the
handle is called before the task is created, the task will bind to the handle once it starts (or restarts).

@param taskId the task id
@param consumer A callback invoked when a sink task processes a record.
@return a non-null {@link TaskHandle}
connect/runtime/src/test/java/org/apache/kafka/connect/integration/ConnectorHandle.java