Mock dependency being initialized with new instance inside constructor

Question

I'm writing test for a class say Producer:

public class Producer {
     ProducerConfig config;
     Repo repo;
     Branch branch;
     .......
     
     @Autowired
     public Producer(Service, repo, branch....) {
         config = new Config(service, branch);
     }

}

So, the dependency in my Producer class is actually being fulfilled by another instance (service) which initialises my ProducerConfig with a new instance instead of a mock. The way I am doing is incorrect and I'm not sure if mocking a constructor would work here like I've shown in next snippet.

How do I get the same mocked ProducerConfig that is being generated in test class and assign it in the Producer constructor?

Test class:

public class ProducerTest {

      @MockBean ProducerConfig config;
      @MockBean Repo repo;
      @MockBean Branch branch;

      Producer producer;
 
      @BeforeEach
      public void init() {
           Service service = Mockito.mock(Service ,class);
           Mockito.doReturn(config).when(new Config(service, branch));
           this.producer = new Producer(service, repo, branch);
      }

}