How to mutate with an empty list

[Matthiasc]

I am new to graphql and the neo4j graphql library and could use some help.
My aim is to create an optional tags fields to BlockTitle

I have the following schema:

type BlockTitle  {
    id: ID! @id 
    created_at: DateTime! @timestamp
    text: String!
    tags: [Tag!]! @relationship(type: "HAS_TAG", direction: OUT)
 }

type Tag {
    id: ID! @id 
    created_at: DateTime! @timestamp
    name: String! @unique
 }

in the neo4j graphql docs I red the following:

The relationship at User.posts is considered a "many" relationship. Relationships such as the one above should always be of type NonNullListType and NonNullNamedType, meaning both the array and the type inside of it should have a !.
neo4j doc ref

Honouring the recommendation I made the tags field accordingly: tags: [Tag!]! ...

But I have trouble mutating the following item (with a tag) in apollo studio:

mutation CreateBlockTitles($input: [BlockTitleCreateInput!]!) {
  createBlockTitles(input: $input) {
    blockTitles {
      text
    }
  }
}

with input

{
  "input": {
    "text": "A title without a tag"
  }
}

which returns following error

  "errors": [
    {
      "message": "BlockTitle.tags required",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
    ...

The things I tried / considered:

1. supplying an empty array [] for the tags field in the mutation but I fail to make that work. I still get the error.
2. using [Tag] instead of [Tag!]!, but going against the recommended practice. So do not really want to do that.

Thank you for the help ❤️