Worklight Adapter getting pdf file from rest service

I am trying to access to a Rest Service who exposes a pdf file, but I get this response when invoking the procedure:

{
   "errors": [
      "Failed to parse the payload from backend (procedure: HttpRequest)"
   ],
   "info": [
   ],
   "isSuccessful": false,
   "responseHeaders": {
      "Content-Type": "application\/octet-stream; type=\"application\/xop+xml\"; boundary=\"uuid:****************\"; start=\"<pdf>\"; start-info=\"application\/pdf\"",
      "Date": "Thu, 07 Nov 2013 14:44:54 GMT",
      "Server": "Apache-Coyote\/1.1",
      "Transfer-Encoding": "chunked",
      "X-Powered-By": "Servlet 2.5; **********",
      "content-disposition": "attachment; filename = ********.PDF"
   },
   "responseTime": 5329,
   "statusCode": 200,
   "statusReason": "OK",
   "totalTime": 9923,
   "warnings": [
   ]
}

Can I get a pdf file using a worklight adapter? is there any alternative way?

I was able to do this with calling a Java routine from the adapter to call the back-end service that returns the PDF as a byte[]. Once the byte[] is retrieved I base64 encode it in the Java routine, URI encode it in the adapter, then do the reverse in the client js code. The Java code uses the Apache HttpClient. I tried the plain return type as well as others with no luck.

Java example here

Adapter code:

var service = new ServiceClient(); 
var pdf = service.getUnsecureContentBase64(url);
result.pdf = encodeURIComponent(pdf);

return result;

Client code:

onSuccess : function (response){

        var pdfText = decodeURIComponent(response.invocationResult.pdf);

        var pdf = base64DecToArr(pdfText);

        //use pdf byte[] to pass to Mozilla pdf.js
        var pdfText = decodeURIComponent(response.invocationResult.pdf);

        var pdf = base64DecToArr(pdfText);

        PDFJS.disableWorker = false;
        PDFJS.getDocument(pdf).then(function (pdfDoc) {
            //use pdfDoc to render
        });
    }

Java code:

public class ServiceClient {

public String getUnsecureContentBase64(String url)
        throws ClientProtocolException, IOException {

    byte[] result = getUnsecureContent(url);

    return Base64.encodeBase64String(result);
}

public byte[] getUnsecureContent(String url)
        throws ClientProtocolException, IOException {

    byte[] result = null;
    CloseableHttpClient httpclient = null;

    try {
        httpclient = HttpClientBuilder.create()
                .setRedirectStrategy(new LaxRedirectStrategy()).build();

        HttpGet httpget = new HttpGet(url);

        // Create a response handler
        ResponseHandler<byte[]> handler = new ResponseHandler<byte[]>() {
            public byte[] handleResponse(HttpResponse response)
                    throws ClientProtocolException, IOException {
                HttpEntity entity = response.getEntity();
                if (entity != null) {
                    return EntityUtils.toByteArray(entity);
                } else {
                    return null;
                }
            }
        };

        result = httpclient.execute(httpget, handler);

    } finally {
        if (httpclient != null) {
            httpclient.close();
        }
    }

    return result;
}
}