code: public int getMessageCount() throws VehicleServiceException {
          if(mRemoteService != null) {
              try {
                  return mRemoteService.getMessageCount();
              } catch(RemoteException e) {
                  throw new VehicleServiceException(
                          "Unable to retrieve message count", e);
              }
          } else {
              throw new VehicleServiceException(
                      "Unable to retrieve message count");
          }
      }
docs: Read the number of messages received by the vehicle service.
  
  @throws VehicleServiceException if the listener is unable to be
  unregistered with the library internals - an exceptional situation
  that shouldn't occur.