Customized error in REST - response entity's body is null even though error was thrown

I have the following REST endpoint:

@PostMapping(path = "/dispatchJob")    public ResponseEntity<Void> dispatchJob(@RequestBody(required = false) JobDispatchRequestBody dispatchRequestBody) throws FailedToAcceptJobException {        modelMapper.getConfiguration().setPropertyCondition(Conditions.isNotNull());        Job j = modelMapper.map(dispatchRequestBody.getDispatchRequestsDTO(), Job.class);        jobsSvc.assignJob(j, dispatchRequestBody.getDispatchEpoch());        return ResponseEntity.noContent().build();    }

The "jobsSvc.assignJob" function throws exception:

    @Override    public synchronized void assignJob(Job j, Long dispatchEpoch) throws FailedToAcceptJobException {        initJobObject(j);        throw new FailedToAcceptJobException(new DispatchJobErrorResponse("System is shutting down, not accepting new job!",                DispatchJobErrorResponse.JobRejectionErrorCode.SystemISShuttingDown));}

And the exception class is as follows:

@Datapublic class FailedToAcceptJobException extends Exception {    private final DispatchJobErrorResponse dispatchJobErrorResponse;    public FailedToAcceptJobException(DispatchJobErrorResponse dispatchJobErrorResponse) {        super("Failed to assign job on agent exception: " + dispatchJobErrorResponse.getMessage());        this.dispatchJobErrorResponse = dispatchJobErrorResponse;    }

I created the following handler that is being called once exception is thrown within this endpoint (I validated that through test):

@ExceptionHandler(value = FailedToAcceptJobException.class)    public ResponseEntity<Object> handleCustomException(HttpServletRequest request,                                                         FailedToAcceptJobException ex)    {        return new ResponseEntity<>(ex.getDispatchJobErrorResponse(),HttpStatus.BAD_REQUEST);    }

My issue is, when I'm trying to call this endpoint via post request, I don't get the body and I can't access the error object (this is a test).

String url = "/dispatchJob";JobDispatchDTO jobDispatchDTO = new JobDispatchDTO();JobDispatchRequestBody dispatchRequestBody = new JobDispatchRequestBody(jobDispatchDTO,1L);ResponseEntity<Void> res = restTemplate.postForEntity(url, dispatchRequestBody,Void.class);

I've been playing with it for hours, I realize that eventually I'll have to use object mapper in order to access "DispatchJobErrorResponse" fields, but the body remains null in the response entity no matter what I do.

Please assist