title: Parse Internal array in list(object) data type in terraform 0.12
body: <p>how can I parse this data type in terraform 0.12</p>
  
  <pre><code> variable "groups" {
      type = list(object({
          group_id = string
          permissions = list(string)
      }))
  }
  </code></pre>
  
  <p>Example:</p>
  
  <pre><code> groups = [
      {
          group_id = "gcp-org-admin"
          permissions = [ "roles/resourcemanager.organizationAdmin",
                          "roles/resourcemanager.folderViewer",
                          "roles/viewer",
                          "roles/iam.organizationRoleViewer",
                          "roles/orgpolicy.policyViewer"
                        ]  
      },
      {
          group_id = "gcp-security-ops"
          permissions = [ "roles/resourcemanager.folderViewer",
                          "roles/logging.viewer",
                          "roles/monitoring.editor",
                          "roles/iam.securityReviewer"
                        ]
      }]
  </code></pre>
  
  <p>for each of the groups, I would like to pair group_id and each permissions
  that is like</p>
  
  <pre><code>  {
      group_id = "gcp-org-admin"
      permissions = "roles/resourcemanager.organizationAdmin"
    },
    {
      group_id = "gcp-org-admin"
      permissions = "roles/resourcemanager.folderViewer"
    },
    {
      group_id = "gcp-org-admin"
      permissions = "roles/viewer"
    }
  </code></pre>
  
  <p>Would like to create organization_iam_resource</p>
  
  <p>for each of the permissions within each group_id, I have to create a resource. </p>
  
  <p>Is there any way to do this</p>