How do I set the provider_id of a Fulfillment Service? by Christian Rohrer

I am trying to create a Fulfillment Service thru the Shopify API. I can set all attributes except the provider_id. I also don't see the provider_id attribute in the API docs: http://docs.shopify.com/api/fulfillmentservice#create

Is it not possible to set the provider_id from outside or is this a bug?