/// <summary>
 /// Does the event stream identified by the domain/type/instance exist yet
 /// </summary>
 public async Task <bool> Exists()
 {
     if (null != _writer)
     {
         return(await _writer.Exists());
     }
     else
     {
         // It cannot exist if the event stream writer was not created
         return(false);
     }
 }