Unable to filter Customer Metafields on namespace and key

[hastinc]

Hi All,

I'm trying to find all metafields for a Customer that has a specific namespace and key
Basically, this cURL request

curl --location --request GET 'https://{{store_domain.com}}/admin/api/2022-01/metafields.json?namespace={{namespace}}&key={{key}}' \
--header 'X-Shopify-Access-Token: {{access_token}}'

In my code I'm using the Customer.ListMetafields method like so:

metafield, err := client.Customer.ListMetafields(shopifyID, goshopify.Metafield{
		Namespace: "{{namespace}}",
		Key:       "{{key}}",
	})
if err != nil {
	lib.CheckError("failed to get Shopify metafield", err)
}

But instead of getting a filtered list of Metafields I'm getting all of the customer's metafields. Is this an issue with the package or am I just doing something silly?