Mockito / Kotlin：内联模拟会改变其行为

Question

将其与代码段进行比较：

val mock = mock<MutableLiveData<UUID>> { on { value } doReturn y }
`when`(x).thenReturn(mock)

和

`when`(x).thenReturn(mock<MutableLiveData<UUID>> { on { value } doReturn y })

为什么第一个代码片段可以正常工作，而第二个代码片段内嵌模拟，为什么会抛出org.mockito.exceptions.misusing.UnfinishedStubbingException？

Mockito错误消息：

org.mockito.exceptions.misusing.UnfinishedStubbingException: 
Unfinished stubbing detected here:
-> at com.xxx.android.ClassTest$testName$1.invokeSuspend(ClassTest.kt:579)

E.g. thenReturn() may be missing.
Examples of correct stubbing:
    when(mock.isOk()).thenReturn(true);
    when(mock.isOk()).thenThrow(exception);
    doThrow(exception).when(mock).someVoidMethod();
Hints:
 1. missing thenReturn()
 2. you are trying to stub a final method, which is not supported
 3: you are stubbing the behaviour of another mock inside before 'thenReturn' instruction if completed

Mockito版本2.22.0， Kotlin版本1.3.31