MEC011: appName it is the only required field when registering the MEC application instance to the MEC platform

According to MEC011 Specification, specifically in Table 7.1.2.6-1 appName is the only mandatory parameter. However, registering an App with the following payload

{
  "appName": "sampleAppName"
}

Returns a 400 Bad Request Error with the following payload.

{
  "status": 400,
  "detail": "Mandatory attribute AppInstanceId is missing."
}

According to the AppInfo data model definition AppInstanceId "shall be present if the application instance is instantiated by the MEC Management.", but "sampleAppName" is not instantiated by the MEC Management. Suggest checking the logic implemented by this endpoint.