Error creating Document: googleapi: Error 400: Missing routing header Terraform GCP Firestore

Question

I am working on using Terraform to create a Firestore DB with a custom name and populate it with a few documents.

If I don't specify a custom name or specify "(default)" everything works perfectly. But if I try to create with a custom db name, I get the following error in Terraform Cloud:

Error: Error creating Document: googleapi: Error 400: Missing routing header. 
Please fill in the request header with format 
x-goog-request-params:project_id=my-project1234&database_id=my-db. 
Please refer to https://firebase.google.com/docs/firestore/manage-databases#access_a_named_database_with_a_client_library for more details.

The doc could not be less helpful:

A named database includes any database not named (default). By default, the Firebase SDKs and Google API Client Libraries connect to the (default) Cloud Firestore database in a project. To create a client connected to a named database, set the database ID when you instantiate a client.

My code:

Terraform:

resource "google_project_service" "firestore" {
  project = var.project_id
  service = "firestore.googleapis.com"

  timeouts {
    create = "30m"
    update = "40m"
  }

  disable_dependent_services = false
  disable_on_destroy         = false
}

resource "google_firestore_database" "database" {
  project     = var.project_id
  name        = var.database_name
  location_id = var.region
  type        = "FIRESTORE_NATIVE"

  depends_on = [google_project_service.firestore]
}

locals {
    DOC1 = jsondecode(file("${path.module}/collections/${var.collection1}/${var.document1}.json"))
}


resource "google_firestore_document" "document" {
    project = var.project_id
    database = google_firestore_database.database.name
    collection = var.collection1
    document_id = var.document1
    fields = jsonencode(local.DOC1)
}

Question:

How do I add a request header in terraform or what else can I do to get past this error?