Strange casts in fuzzed Spring tests, sometimes leading to compilation errors

[EgorkaKulikov]

Description

Run unit tests generation for PetController class in spring-petclinic application.
Use standard settings, just click OK on UI.

Actual behavior

The following test is generated (there are more than ten strange tests, this is just an example):

 @Test
 public void testProcessCreationFormByFuzzer1() {
 Owner ownerMock = mock(Owner.class);
 (((Owner) (doNothing()).when(ownerMock))).addPet(any());
 Pet petMock = mock(Pet.class);
 (when(petMock.getName())).thenReturn("duplicate");
 (when(petMock.isNew())).thenReturn(false);
 LocalDate localDateMock = mock(LocalDate.class);
 (when(localDateMock.isAfter(any()))).thenReturn(true);
 (when(petMock.getBirthDate())).thenReturn(localDateMock);
 BindingResult resultMock = mock(BindingResult.class);
 (((Errors) (doNothing()).when(resultMock))).rejectValue(any(), any());
 (when(resultMock.hasErrors())).thenReturn(true);
 ModelMap model = new ModelMap();
 OwnerRepository ownersMock = mock(OwnerRepository.class);
 PetController petController = new PetController(ownersMock);
 model.put(((Object) "abc"), ((Object) petController));

 String actual = petController.processCreationForm(ownerMock, petMock, resultMock, model);

 String expected = "pets/createOrUpdatePetForm";

 assertEquals(expected, actual);
 }

Note that there are two types of strange casts: to Object and to Owner/Errors. One of them leads to compilation error.

Additional context

Kirill says that this bug also reproduces on October release.

[EgorkaKulikov]

@IlyaMuravjov may be you now why does it happen?