def METHOD_NAME(
    self,
    cls,
    data,
    api_key=djstripe_settings.STRIPE_SECRET_KEY,
    pending_relations=None,
):
    from ..event_handlers import update_customer_helper
    super().METHOD_NAME(
        cls, data, api_key=api_key, pending_relations=pending_relations
    )
    # only update if customer and metadata exist
    if self.customer and self.metadata:
        key = djstripe_settings.SUBSCRIBER_CUSTOMER_KEY
        current_value = self.metadata.get(key)
        # only update if metadata has the SUBSCRIBER_CUSTOMER_KEY
        if current_value:
            metadata = {key: current_value}
            # Update the customer with ONLY the customer specific metadata
            update_customer_helper(
                metadata,
                self.customer.id,
                key,
            )
            # Update metadata in the Upstream Customer Object on Stripe
            self.customer._api_update(metadata=metadata)