private void OnEngineChanged(object sender, EngineChangedEventArgs engineChangedEventArgs)
        {
            // Clear existing entities
            for (var i = _contents.Count - 1; i >= 0; i--)
            {
                RemoveEntity(_contents[i]);
            }

            // Add new entities
            foreach (var newEntity in engineChangedEventArgs.NewEngine.Entities)
            {
                if (Filter.Filter(newEntity))
                {
                    AddEntity(newEntity);
                }
            }
        }
 /// <summary>
 /// Invoked when Speech-to-Text engine has been changed
 /// </summary>
 /// <param name="sender">object</param>
 /// <param name="e">EngineChangedEventArgs</param>
 private void _Stt_EngineChanged(object sender, EngineChangedEventArgs e)
 {
     Console.WriteLine(" ----_Stt_EngineChanged : " + e.EngineId + ", " + e.Language + ", " + e.NeedCredential + ", " + e.SupportSilence);
 }