Angularjs : call to REST API to get a docx document from server - angularjs

Question

I am trying to call a service from angularjs that produces a docx document.
Angularjs is supposed to display the save prompt of the web browser, and then save the document.
When I open the saved document, what I get in the docx file is :
Undefined
Api rest :
#RequestMapping(value = "/create-avenant",
method = RequestMethod.POST,
produces = MediaType.APPLICATION_JSON_VALUE)
#Timed
public void getAvenant(#RequestBody AvenantDTO avenant, HttpServletResponse response) {
contratService.createAvenant(response, avenant);
}
service produces a XWPFDocument and send to browser :
private void sendDocToBrowser(HttpServletResponse response, XWPFDocument doc) throws IOException {
try
{
byte[] buffer = new byte[8192];
ByteArrayOutputStream baos = new ByteArrayOutputStream();
doc.write(baos);
response.setHeader("Content-Disposition", "attachment;filename=myDoc.docx");
response.setContentType("application/docx");
ServletOutputStream outputStream = response.getOutputStream();
baos.writeTo(outputStream);
outputStream.flush();
}
finally
{
outputStream.close();
}
}
Angularjs :
Avenant.create(avenant,function(result){
var blob = new Blob([result.body], { type: 'application/docx' });
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = 'file.docx';
link.click();
})