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));
        }