Send empty JSON objet to API

For lab purpose I have to send a JSON object containing others objects and one of them has no property (empty) as you can see :

{
     "id": "00u12e3knx76B4PNS4x7",
     "scope": "USER",
     "credentials": {
     "userName": "some@email.com"
     },
     "profile": {}
}

I'm using Java Jersey and POJO to generate Java classes from JSON payloads but I cannot find what to send in this case match my API requirement.

Here is my code sample :

@POST
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response eventHook(String body, @HeaderParam("Pass") String password) {
    ObjectMapper objectMapper = new ObjectMapper();
    RequestPayload requestPayload = new RequestPayload();

    writeLogger(body);

    try {
        requestPayload = objectMapper.readValue(body, RequestPayload.class);
    } catch (JsonProcessingException e) {
        e.printStackTrace();
    }

    EventsItem event = requestPayload.getData().getEvents().get(0);

    TargetItem targetItem = event.getTarget().get(2);

    RequestApiAssignUser user = new RequestApiAssignUser();

    Credentials credentials = new Credentials();
    credentials.setUserName("id");
    user.setId(getUser.getId());
    user.setScope("USER");
    user.setCredentials(credentials);

    Profile profile = new Profile();
    user.setProfile(profile);

    Response postResponse = ClientBuilder.newClient()
            .target(API_URL)
            .path("apps/" + getApps("0oa13t5dqnkYGDZEd4x7") + "/users")
            .request(MediaType.APPLICATION_JSON)
            .header(HttpHeaders.AUTHORIZATION, "SSWS " + API_TOKEN)
            .post(Entity.entity(user, MediaType.APPLICATION_JSON));

    String responseAPI = postResponse.readEntity(String.class);

    return Response.status(200).entity(responseAPI).build();

Here is the error due to the imposssibility to serialize Profile Object because it has no properties :

> jakarta.ws.rs.ProcessingException:
> com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No
> serializer found for class
> Payload.Api.Apps.Post.Assign.Request.Profile and no properties
> discovered to create BeanSerializer (to avoid exception, disable
> SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain:
> Payload.Api.Apps.Post.Assign.Request.RequestApiAssignUser["profile"])

Thanks !

The error is telling you to disable the SerializationFeature.FAIL_ON_EMPTY_BEANS property on the ObjectMapper. Normally to configure the ObjectMapper with Jersey, you would implement a ContextResolver. The the Jackson ObjectMapper that's used under the hood would look this resolver up and configure the property.

But in this case, you already are using a mapper in your code. So I would just configure that mapper and then serialize the User object into a String and use that JSON string as the entity

objectMapper.disable(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS);

Then at the bottom before your client code just serialize the User to a string.

String userJson = objectMapper.writeValueAsString(user);
Response postResponse = ClientBuilder.newClient()
            ...
            .post(Entity.entity(userJson, MediaType.APPLICATION_JSON));

In other cases, if you did not already have an ObjectMapper, you would implement a ContextResolver as I mentioned above.

public class ObjectMapperResolver implements ContextResolver<ObjectMapper> {

    private final ObjectMapper mapper = new ObjectMapper();

    public ObjectMapperResolver() {
        mapper.disable(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS);
    }

    @Override
    public ObjectMapper getContext(Class<?> cls) {
        return mapper;
    }
}

Then you would register this with the client

Response postResponse = ClientBuilder.newClient()
        .register(ObjectMapperResolver.class)
        ...

You created Credentials() object and this is a empty object but you setted userName, now is not empty. Credentials object have a userName variable. But your created Profile() object is empty. And you did not set any variable to this Profile() object. You setted Profile() object to empty Profile() object. You need set a real variable.