API does not return device metadata (update metadata not working)

Hello,

I recognised that the endpoint to retrieve a device by id does not return the metadata added to attributes as documented
in the nodelib docs.

This happens although the metadata is correctly posted to the create endpoint and the referenced entity is correctly initialised:

How to reproduce:

I sent this payload to the create endpoint:

"devices": [
    {
      "device_id": "device_with_meta",
      "service": null,
      "service_path": "/",
      "entity_name": "test_entity",
      "entity_type": "test_entity_type",
      "timezone": "Europe/Berlin",
      "timestamp": null,
      "apikey": "1234",
      "endpoint": null,
      "protocol": null,
      "transport": "HTTP",
      "lazy": [],
      "commands": [],
      "attributes": [
        {
          "name": "temperature",
          "type": "Number",
          "metadata": {
            "accuracy": {
              "type": "Text",
              "value": "+-5%"
            }
          },
          "expression": null,
          "entity_name": null,
          "entity_type": null,
          "reverse": null,
          "object_id": "temperature"
        }
      ],
      "static_attributes": [],
      "internal_attributes": null,
      "expressionLanguage": null,
      "explicitAttrs": false,
      "ngsiVersion": "v2"
    }
]

The created then entity looks like this:

    {
      "id": "test_entity",
      "type": "test_entity_type",
      "TimeInstant": {
        "type": "DateTime",
        "value": "2021-05-06T07:34:20.417Z",
        "metadata": {}
      },
      "temperature": {
        "type": "Number",
        "value": null,
        "metadata": {
          "accuracy": {
            "type": "Text",
            "value": "+-5%"
          }
        }
      }
    }

However, retrieving the device by its id returns this:

{
  "device_id": "device_with_meta",
  "service": "filip",
  "service_path": "/testing",
  "entity_name": "test_entity",
  "entity_type": "test_entity_type",
  "apikey": "1234",
  "transport": "HTTP",
  "lazy": [],
  "commands": [],
  "attributes": [
    {
      "name": "temperature",
      "type": "Number",
      "object_id": "temperature"
    }
  ],
  "static_attributes": [],
  "explicitAttrs": false,
  "ngsiVersion": "v2"
}

Am I missing an undocumented query parameter here or is it just a bug?

Start with the device creation and retrieve-by-ID API entry points described in the nodelib API documentation, then reproduce the request using the supplied payload. Compare the returned device attributes with the entity shown in the issue, focusing on whether metadata is dropped during retrieval. Done means the retrieve response includes the attribute metadata posted during creation.