ApiExceptionMapper.java

@Provider
public class ApiExceptionMapper implements ExceptionMapper<ApiException> {

    @Override
    public Response toResponse(ApiException ex) {

        ErrorEntity error = new ErrorEntity();
        error.setStatus(ex.getStatus());
        error.setMessage(ex.getMessage());
        error.setDeveloperMessage(ex.getMessage());

        return Response.status(ex.getStatus())
                .entity(error)
                .type(MediaType.APPLICATION_JSON)
                .build();
    }
}

GenericExceptionMapper.java

@Provider
public class GenericExceptionMapper implements ExceptionMapper<Throwable> {

    @Override
    public Response toResponse(Throwable ex) {

        ErrorEntity error = new ErrorEntity();
        setHttpStatus(ex, error);
        error.setMessage(ex.getMessage());
        StringWriter errorStackTrace = new StringWriter();
        ex.printStackTrace(new PrintWriter(errorStackTrace));
        error.setDeveloperMessage(errorStackTrace.toString());

        return Response.status(error.getStatus())
                .entity(error)
                .type(MediaType.APPLICATION_JSON)
                .build();
    }

    private void setHttpStatus(Throwable ex, ErrorEntity error) {
        if(ex instanceof WebApplicationException) {
            error.setStatus(( (WebApplicationException) ex).getResponse().getStatus());
        } else {
            error.setStatus(Response.Status.INTERNAL_SERVER_ERROR.getStatusCode());
        }
    }
}