GWT download byte[]

Question

Can you help me I have PDF file in byte[] I get it from resty-gwt

@Produces({ MediaType.APPLICATION_JSON })
@Consumes({ MediaType.APPLICATION_JSON })

    @Path("/report")
    @POST
    void report(String id, JsonCallback jsonCallback);

So I have JSON

{
    "report": "..."
    }

How can I download it???