title: gRPC context.interceptCall() and SimpleForwardingServerCallListener
body: <ol>
  <li><p>Can someone explain or point me into the right direction where I can understand when to use ForwardingServerCallListener.SimpleForwardingServerCallListener or Contexts.interceptCall in gRPC intercept call on the server side.</p></li>
  <li><p>In REST a thread gets associated with a request and does the same happen in gRPC too or when a request gets delegated a new thread is created?</p></li>
  </ol>