Improve CustomObjectMarshaller resolution #1271

@Test
void testCustomMarshallers() {
  CustomObjectMarshaller personMarshaller = Mockito.spy(CustomObjectMarshaller.class);
  Mockito.when(personMarshaller.priority()).thenReturn(1);
  Mockito.when(personMarshaller.getObjectClass()).thenReturn(Person.class);
  CustomObjectMarshaller employeeMarshaller = Mockito.spy(CustomObjectMarshaller.class);
  Mockito.when(employeeMarshaller.priority()).thenReturn(2);
  Mockito.when(employeeMarshaller.getObjectClass()).thenReturn(Employee.class);
  CustomObjectMarshaller objectMarshaller = Mockito.spy(CustomObjectMarshaller.class);
  Mockito.when(objectMarshaller.priority()).thenReturn(1);
  Mockito.when(objectMarshaller.getObjectClass()).thenReturn(Object.class);
  Object employee = new Employee();
  Object student = new Student();
  Object person = new Person();
  Object other = new byte[2];

  List<CustomObjectMarshaller> marshallers =
      Stream.of(objectMarshaller, employeeMarshaller, personMarshaller)
          .sorted()
          .collect(Collectors.toList());
  assertThat(marshallers).containsExactly(objectMarshaller, personMarshaller, employeeMarshaller);
  assertThat(MarshallingUtils.getCustomMarshaller(marshallers, employee.getClass()))
      .isEqualTo(employeeMarshaller);
  assertThat(MarshallingUtils.getCustomMarshaller(marshallers, person.getClass()))
      .isEqualTo(personMarshaller);
  assertThat(MarshallingUtils.getCustomMarshaller(marshallers, other.getClass()))
      .isEqualTo(objectMarshaller);
  assertThat(MarshallingUtils.getCustomMarshaller(marshallers, student.getClass()))
  .isEqualTo(employeeMarshaller);
}
}