Heat Update Stack Preview does not contain flavor and volume details for newly added server resources (os::nova::server)

API used:
/v1/{tenant_id}/stacks/{stack_name}/{stack_id}/preview
Preview stack update

URL for API:
https://developer.openstack.org/api-ref/orchestration/v1/?expanded=list-stack-resources-detail,list-stacks-detail,delete-stack-detail,suspend-stack-detail,preview-stack-update-detail,preview-stack-detail,create-stack-detail

Here you can see , in "added": [ { "attributes": " it does not contain "flavor", "os-extended-volumes:volumes_attached" for newly added server resource(os::nova::server). here we can see only 8 attributes though in case of delete resources it has many attributes. From stack update preview point of view, it is really essential to have flavor and volume information. please revert.

"added": [
      {
        "attributes": {
          "accessIPv4": "",
          "accessIPv6": "",
          "addresses": "",
          "console_urls": "",
          "first_address": "",
          "instance_name": "",
          "name": null,
          "networks": ""
        },
        "creation_time": null,
        "description": "",
        "metadata": {},
        "physical_resource_id": "",
        "required_by": [],
        "resource_action": "INIT",
        "resource_identity": {
          "path": "/resources/instancegovmai1n-",
          "stack_id": "39480208-ac12-4023-8cc8-3ce460b33fc0",
          "stack_name": "Single-Server-Stack",
          "tenant": "68dee30f86344f14a650d0c75813801d"
        },
        "resource_name": "instancegovmai1n-",
        "resource_status": "COMPLETE",
        "resource_status_reason": "",
        "resource_type": "OS::Nova::Server",
        "stack_identity": {
          "path": "",
          "stack_id": "39480208-ac12-4023-8cc8-3ce460b33fc0",
          "stack_name": "Single-Server-Stack",
          "tenant": "68dee30f86344f14a650d0c75813801d"
        },
        "stack_name": "Single-Server-Stack",
        "updated_time": null
      }
    ],

"deleted": [
      {
        "attributes": {
          "OS-DCF:diskConfig": "MANUAL",
          "OS-EXT-AZ:availability_zone": "nova",
          "OS-EXT-STS:power_state": 1,
          "OS-EXT-STS:task_state": null,
          "OS-EXT-STS:vm_state": "active",
          "OS-SRV-USG:launched_at": "2017-05-08T15:06:51.000000",
          "OS-SRV-USG:terminated_at": null,
          "accessIPv4": "",
          "accessIPv6": "",
          "addresses": {
            "AFR-ECOMPNETWORK": [
              {
                "OS-EXT-IPS-MAC:mac_addr": "fa:16:3e:52:9b:90",
                "OS-EXT-IPS:type": "fixed",
                "addr": "10.10.1.190",
                "version": 4
              }
            ]
          },
          "config_drive": "",
          "created": "2017-05-08T15:06:38Z",
          "flavor": {
            "id": "205bb2df-d4fa-4478-bf97-cb2e69d440b5",
            "links": [
              {
                "href": "http://131.160.203.5:8774/68dee30f86344f14a650d0c75813801d/flavors/205bb2df-d4fa-4478-bf97-cb2e69d440b5",
                "rel": "bookmark"
              }
            ]
          },
          "hostId": "b9efc004da62170279dd147ff6f558326b91fbf43d6b09b741c2661b",
          "id": "d866e593-5552-4614-81ee-f8e5e060a0b0",
          "image": {
            "id": "26b9f717-137e-41e0-adbe-78346f72ba63",
            "links": [
              {
                "href": "http://131.160.203.5:8774/68dee30f86344f14a650d0c75813801d/images/26b9f717-137e-41e0-adbe-78346f72ba63",
                "rel": "bookmark"
              }
            ]
          },
          "key_name": null,
          "links": [
            {
              "href": "http://131.160.203.5:8774/v2.1/68dee30f86344f14a650d0c75813801d/servers/d866e593-5552-4614-81ee-f8e5e060a0b0",
              "rel": "self"
            },
            {
              "href": "http://131.160.203.5:8774/68dee30f86344f14a650d0c75813801d/servers/d866e593-5552-4614-81ee-f8e5e060a0b0",
              "rel": "bookmark"
            }
          ],
          "metadata": {},
          "name": "Single-Server-Stack-instancegovmain--wpnwnmf3k2xz",
          "os-extended-volumes:volumes_attached": [
            {
              "id": "c1e4e0eb-b3e7-4d9c-b197-51fe629c455f"
            }
          ],
          "progress": 0,
          "security_groups": [
            {
              "name": "default"
            }
          ],
          "status": "ACTIVE",
          "tenant_id": "68dee30f86344f14a650d0c75813801d",
          "updated": "2017-05-08T15:06:51Z",
          "user_id": "51c410747d4a4114b88c4a72e1ddce87"
        },
        "creation_time": "2017-05-08T15:06:36",
        "description": "",
        "metadata": {},
        "physical_resource_id": "d866e593-5552-4614-81ee-f8e5e060a0b0",
        "required_by": [
          "volume_attachment"
        ],
        "resource_action": "CREATE",
        "resource_identity": {
          "path": "/resources/instancegovmain-",
          "stack_id": "39480208-ac12-4023-8cc8-3ce460b33fc0",
          "stack_name": "Single-Server-Stack",
          "tenant": "68dee30f86344f14a650d0c75813801d"
        },
        "resource_name": "instancegovmain-",
        "resource_status": "COMPLETE",
        "resource_status_reason": "state changed",
        "resource_type": "OS::Nova::Server",
        "stack_identity": {
          "path": "",
          "stack_id": "39480208-ac12-4023-8cc8-3ce460b33fc0",
          "stack_name": "Single-Server-Stack",
          "tenant": "68dee30f86344f14a650d0c75813801d"
        },
        "stack_name": "Single-Server-Stack",
        "updated_time": "2017-05-08T15:06:36"
      },