packer/command/test-fixtures/hcl2_upgrade/undeclared-variables/input.json

{
    "variables": {
        "foo": "bar"
    }, 
    "builders": [
        {
        "type": "null",
        "communicator": "{{ user `communicator_type` }}"
        }
    ],
    "provisioners": [
        {
            "type": "shell",
            "script": "{{user `scriptpath`}}"
        }
    ]
}