WABP: incoming system message

[nbartels]

{
  "object": "whatsapp_business_account",
  "entry": [
    {
      "id": "101809759215303",
      "changes": [
        {
          "value": {
            "messaging_product": "whatsapp",
            "metadata": {
              "display_phone_number": "123456789",
              "phone_number_id": "1063423435420583"
            },
            "contacts": [
              {
                "profile": {
                  "name": "TestUser"
                },
                "wa_id": "491234567890"
              }
            ],
            "messages": [
              {
                "from": "491234567890",
                "id": "wamid.HBgNNDkxNTIwOTgzMzMGDHEVFEJHFCIYFDNBMUNCMzAwRTQ5RDBDRUE4NzJDAA==",
                "timestamp": "1653318440",
                "type": "system",
                "system": {
                    "body": "NAME changed from PHONE_NUMBER to PHONE_NUMBER",
                    "new_wa_id": NEW_PHONE_NUMBER,
                    "type": "user_changed_number"
                  },
              }
            ]
          },
          "field": "messages"
        }
      ]
    }
  ]
}