hcl variables: return an unknown value in when no default is set
hcl variables: return an unknown value in when no default is set

mitchellh/packer,ricardclau/packer,ricardclau/packer,ricardclau/packer,rnaveiras/packer,pecigonzalo/packer,hashicorp/packer,hashicorp/packer,rnaveiras/packer,ricardclau/packer,ricardclau/packer,mitchellh/packer,rnaveiras/packer,pecigonzalo/packer,mitchellh/packer,rnaveiras/packer,rnaveiras/packer,rnaveiras/packer,ricardclau/packer,pecigonzalo/packer,mitchellh/packer,pecigonzalo/packer,mitchellh/packer,hashicorp/packer,hashicorp/packer