jersey 2.0 jaxrs RI - return json string on exception - rest

Question

I am creating a REST service using jersey 2.0. I am extending WebApplicationException
Method raising a particular exception
if(json.equals("") || json.equals(" ")) {
throw new ArgumentException("bad post data");
}
public class ArgumentException extends RestException {
.....
public ArgumentException(String message) {
super(Status.BAD_REQUEST,message);
}
}
public class RestException extends WebApplicationException {
...........
public RestException(Status status, String message) {
super(Response.status(status)
.entity(message)
.type("text/plain")
.build());
/*
super(Response.status(status)
.entity(new ErrorBean(status.getStatusCode(),message))
.type(MediaType.APPLICATION_JSON)
.build()); */
}
ErrorBean is a POJO
The method that returns error as plain string inside RestException works (right http code 400 and message). However when I try to pass the ErrorBean POJO and use MediaType.APPLICATION_JSON in response I get an error saying "Headers have already been sent" with http error code 500 (so some internal problem with plumbing) and empty response.
I have also looked at this question Returning JSON or XML for Exceptions in Jersey
How can I return the exception with code and message as a JSON like
{"code" : 400, "message" : .... }
Update
I have received answer on SO as well as jersey users mailing list. steps are
A non AJXB POJO does not need any annotations
Register JacksonFeature in your application
ResourceConfig rc = new ResourceConfig().packages("test").register(JacksonFeature.class);

Answer 1

You need to register JacksonFeature in your Application/ResourceConfig, i.e.:
// Create JAX-RS application.
final Application application = new ResourceConfig()
.packages("org.glassfish.jersey.examples.jackson")
.register(JacksonFeature.class)
// No need to register this provider if no special configuration is required.
.register(MyObjectMapperProvider.class);
Take a look at the documentation for Jackson support in Jersey and also at the example.