首先，AnswersWithDelay是Mockito的一个内部类，所以不应该直接使用它。该类的示例应该通过使用公共AdditionalAnswers类中的工厂方法来创建。
所以你只需要

doAnswer(AdditionalAnswers.answersWithDelay(delay, invocation -> null)).when(mockObject).doSomething();

基于this的回答，用草稿测试类。

@ExtendWith(SpringExtension.class)
public class MockDelayVoidTest {

    @MockBean
    private Object myMock;

    void test(){
        Mockito.doAnswer(AdditionalAnswers.answersWithDelay(1000, invocationOnMock -> {
            //here you can customize the behavior of your mock method
            return null;}))
                .when(myMock).toString();
    }
}

另一种方式可以是，

Mockito.doAnswer(invocation -> {
        TimeUnit.SECONDS.sleep(5);
        return null;
    }).when(mock).doSomething();