public IList <XpsDigitalSignature> GetDocumentSignatures(string documentId)
{
var actor = HttpContext.GetTokenActor();
var api = _contextService.GetServerApi(actor);
var guid = Guid.Parse(documentId);
var xpsServiceApi = _contextService.GetExternalXpsServiceApi(api);
var signatureBuffer = xpsServiceApi.GetSignatures(guid);
return(DtoCreator.CreateDigitalSignatures(signatureBuffer));
}