Terraform apply to a Neptune resource says there is nothing to do

Terraform Providers AWS
1

When I execute terraform apply to the following resources I get back.

Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

resource "aws_neptune_cluster" "example" {
}
  cluster_identifier                  = "neptune-cluster-test"
  engine                              = "neptune"
  engine_version                      = "1.1.1.0.R7"
  port                                = "8182"
  backup_retention_period             = 1
  preferred_backup_window             = "07:00-09:00"
  skip_final_snapshot                 = true
  apply_immediately                   = true
}


resource "aws_neptune_cluster_instance" "example" {
  count              = 2
  cluster_identifier = aws_neptune_cluster.default.id
  engine             = "neptune"
  instance_class     = "db.r4.large"
  apply_immediately  = true
}
2

Also when I run terraform plan for the first time I see the following.

No changes. Your infrastructure matches the configuration.

Terraform has compared your real infrastructure against your configuration and found no differences, so no changes are needed.