code: @Override
    public synchronized void onNext(final RuntimeStart runtimeStart) {
      LOG.log(Level.FINEST, "HttpRuntimeStartHandler: {0}", runtimeStart);
      try {
        httpServer.start();
        LOG.log(Level.FINEST, "HttpRuntimeStartHandler complete.");
      } catch (final Exception e) {
        LOG.log(Level.SEVERE, "HttpRuntimeStartHandler cannot start the Server. {0}", e);
        throw new RuntimeException("HttpRuntimeStartHandler cannot start the Server.", e);
      }
    }
docs: Override EventHandler<RuntimeStart>.
  
  @param runtimeStart