I'm unable to update a metafield of type file list

[mihaiav]

I have a product with a custom metafield of type list of files .
I've tried the following to pass information (some images):

        shop.Metafield{
			Key:       key,
			Namespace: ns,
			Value:    `["gid://shopify/ProductImage/66131787907409"]`,
			Type: shop.MetafieldType("list.file_reference"),
		}

I get the error
metafields.value: must be a file reference string.

For debugging purposes I also tried only one value/string

           shop.Metafield{
			Key:       key,
			Namespace: ns,
			Value:    `"gid://shopify/ProductImage/66131787907409"`,
			Type: shop.MetafieldType("list.file_reference"),
		}

I get the error: metafields.value: must be an array.

Also tried:

              shop.Metafield{
			Key:       key,
			Namespace: ns,
			Value:    []string{"gid://shopify/ProductImage/66131787907409"},
			Type: shop.MetafieldType("list.file_reference"),
		}

I get error value: expected Array to be a String

Any idea how am I supposed to pass a list of files (images) ? This drives me absolutely crazy! I've spent 4 hours trying to fix this...