title: What happens to Azure IoT Hub Direct Method invocation if there is no handler
body: <p>I'm using Azure IoT Hub with a C# desktop application client. I introduced a new Direct Method invocation on the server and also added a handler to a new client version.
  But I'm wondering what would happen to old clients that do not have a handler for this direct method if I publish the changes to the backend.</p>
  
  <p>Would this result in an exception and so a crash or would the invocation be ignored?
  I tried searching for answers to this question here on SO and elsewhere but couldn't find any answers.</p>