compare Set<Long> that contains integers to Set<Long>

I have a controller that returns a Set<Long> in its response`s body :

public ResponseEntity<?> getIds(){
    Set<Long> ids =  someFunc(..);
    return ResponseEntity.ok(ids);
}

In my test I'm trying to compare the result of the rest call to a different Set<Long>

MockHttpServletResponse result = mockMvc.perform(.....).andReturn().getResponse();
Set<Long> responseBody  = objectMapper.readValue(result.getContentAsByteArray(), Set.class);
responseBody = responseBody.stream().map(number->number.longValue()).collect(Collectors.toSet());
assertThat(responseBody.equals(otherSet),is(true));

When I run the code in debug mode I saw that the responseBody contains Integer objects.

The error that I'm getting on the line with the mapping (map(number->number.longValue())) :

java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.Long (java.lang.Integer and java.lang.Long are in module java.base of loader 'bootstrap')

It seems that the object mapper convert the Long objects (ids) to Integer objects because it can fit into an integer..

I know that I can use :

new ObjectMapper().configure(DeserializationFeature.USE_LONG_FOR_INTS,true);

but I want to find a solution that will convert the value and not add a constraint on my mapper.

You can read your data as Set<Long>. Use TypeReference to specify the type you want to read, then you don't need to convert Integer into Long

Set<Long> responseBody  = objectMapper.readValue(result.getContentAsByteArray(),
                                                      new TypeReference<Set<Long>>(){});