## params
...
  data_nodes: 2
  volumes:
    volume_id-1: 3c975879-3733-4ce7-92b4-98a05e30c8f0
    volume_id-2: 82793e2f-46df-4808-a995-b3d157d91b91
...

## HEAT_01.yaml
...
  data_node_group:
    type: OS::Heat::ResourceGroup
    properties:
      count: { get_param: data_nodes }
      resource_def:
        type: ORG::Type
        properties:
          node_name: { list_join: ['-', [ { get_param: 'OS::stack_name' }, 'data', '%index%'] ] } # {name}-data-X
          volume_id: { get_param: [volumes, volume_id_%index%] }
          #volume_id: { get_param: [volumes, volume_id_1] } #WORKS!!
...

## ORG::Type yaml:
...
  data_volume_attachment:
    type: OS::Cinder::VolumeAttachment
    properties:
      volume_id: { get_param: volume_id }
      instance_uuid: { get_resource: node }
...

## Stack FAILURE:
| stack_status          | CREATE_FAILED
| stack_status_reason   | Resource CREATE failed: StackValidationFailed:
|                       | resources.data_node_group.resources[1]: Error
|                       | validating value u'': The Volume () could not be found.