public async Task <Models.DigitalIdentity> GetIdentityForCustomerAsync(Guid customerId)
        {
            var collectionUri = DocumentDBHelper.CreateDigitalIdentityDocumentUri();
            var client        = DocumentDBClient.CreateDocumentClient();

            var identityForCustomerQuery = client
                                           ?.CreateDocumentQuery <Models.DigitalIdentity>(collectionUri, new FeedOptions {
                MaxItemCount = 1
            })
                                           .Where(x => x.CustomerId == customerId)
                                           .AsDocumentQuery();

            if (identityForCustomerQuery == null)
            {
                return(null);
            }

            var digitalIdentity = await identityForCustomerQuery.ExecuteNextAsync <Models.DigitalIdentity>();

            return(digitalIdentity?.FirstOrDefault());
        }