title: Stripe client_reference_id: null in checkout.session.completed
body: <p>I have a stripe pricing table on my front end to render the options available to customers. On my backend I am using Django to handle account creation if the payment was successful. As below this was created following a tutorial on TestDriven.io btw.</p>
  <pre><code>if event['type'] == 'checkout.session.completed':
          session = event['data']['object']
          print(session)
          # # Fetch all the required data from session
          client_reference_id = session.get('client_reference_id')
          stripe_customer_id = session.get('customer')
          stripe_subscription_id = session.get('subscription')
  
          # Get the user and create a new StripeCustomer
          user = CustomUser.objects.get(id=client_reference_id)
          StripeCustomer.objects.create(
              user=user,
              stripeCustomerId=stripe_customer_id,
              stripeSubscriptionId=stripe_subscription_id,
          )
  
  </code></pre>
  <p>I am getting the following error</p>
  <pre><code>raise self.model.DoesNotExist(apps.authentication.models.CustomUser.DoesNotExist: CustomUser matching query does not exist
  </code></pre>
  <p>So after some digging I have found that Stripe is not returning the client_reference_id to my backend, below is a printout of the session variable</p>
  <pre><code>&quot;client_reference_id&quot;: null,
  </code></pre>
  <p>I believe this is why the account is not being found by Django, but I can't seem to figure out why Stripe isn't sending this information over or how to attach it to the response to my Web hook?</p>