actions.subscription.create - how do i pass metadata?

[kolektiv]

Using the react paypal button, <PayPalButton >,

how do i send metadata about who this user is that is creating a subscription all the way through to my webhook so that my server side API can receive both the confirmation from paypal's webhook event AND the data about our internal user id?

are there any paramaters i can send in the createSubscription that pass through? I see that for creating orders, you can pass meta detail in the order details.

createSubscription(data, actions) {

   return actions.subscription.create({
       'plan_id': 'P-XXX',

   })

}