Make Spring-specific no NPE speculation to only trigger for mocks

[IlyaMuravjov]

Description

In Spring-specific unit tests class under test field can't be mocks in one execution and null in another due to @InjectMock either always injecting or non injecting the mocks into class under test.

How to test

Manual tests

• Open spring-boot-testing project.
• Generate unit tests using Mock everything outside the class strategy for the following classes.

There should be NPE tests for equals() in the following class:

@Getter
@Setter
@Builder
@ToString
@Jacksonized
@NoArgsConstructor
@AllArgsConstructor
@Entity
@EqualsAndHashCode
@Table(name = "orders")
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Long id;

    @Email
    @NotEmpty
    String buyer;
    Double price;
    int qty;

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || !(o instanceof Order)) return false;
        Order order = (Order) o;
        return qty == order.qty && id.equals(order.id) && buyer.equals(order.buyer) && price.equals(order.price);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, buyer, price, qty);
    }
}

There should be no NPE tests for createOrder() in the following class

@Service
public class OrderService {
    private final OrderRepository orderRepository;

    public Order createOrder(Order order) {
        return orderRepository.save(order);
    }
}

Self-check list

• I've set the proper labels for my PR (at least, for category and component).
• PR title and description are clear and intelligible.
• I've added enough comments to my code, particularly in hard-to-understand areas.
• The functionality I've repaired, changed or added is covered with automated tests.
• Manual tests have been provided optionally.
• The documentation for the functionality I've been working on is up-to-date.

[IlyaMuravjov]

On second thought we can't rely solely on the fact that engine decided to mock or not to mock some fields, since fuzzer may do mocking differently, so I think we should do some execution filtering after the generation has completed.

[IlyaMuravjov]

Replaced with #2617