Append can't be accepted as a variable

[captn3m0]

Terraform Version

terraform --version
Terraform v0.11.11
+ provider.ignition v1.0.1
+ provider.null v2.0.0

Affected Resource(s)

Please list the resources as a list, for example:

• ignition_config

Terraform Configuration Files

https://github.com/captn3m0/ignition-bug-report

Debug Output

https://paste.ubuntu.com/p/grzKJn3P7D/

Expected Behavior

append should accept a list of maps from a variable.

Actual Behavior

Error: data.ignition_config.main: "append.0.source": required field is not set

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

1. git clone git@github.com:captn3m0/ignition-bug-report.git
2. cd ignition-bug-report
3. terraform init && terraform plan

The basic idea is to get

data "ignition_config" "main" {
  append = ["${module.name.conf}"]
}

working. But append doesn't like taking its value from a external source.