[解決事件] Mockitoのでメソッドの戻り値を指定するとNullPointerExceptionが発生する

interface Specification {
  boolean isSatisfiedBy(User user);
}

@Test
void test() {
  ...
  Specification specification = mock(Specification.class);
  when(specification.isSatisfiedBy(any())).thenReturn(true);
  ...
}

interface Specification {
  boolean isSatisfiedBy(User user, int revision);
}

@Test
void test() {
  ...
  Specification specification = mock(Specification.class);
  when(specification.isSatisfiedBy(any(), any())).thenReturn(true);
  ...
}