aspnetcore/test/TestSites/CreateDefaultBuilderOfTApp/appsettings.json

{
  "settingsKey": "settingsValue",
  "AllowedHosts":  "example.com;127.0.0.1",
  "Kestrel": {
    "Endpoints": {
      "HTTP": {
        "Url": "http://127.0.0.1:0",
        "KestrelEndPointSettingName": "KestrelEndPointSettingValue"
      }
    }
  }
}