code: protected void async(final AsyncManager asyncManager, final Runnable runnable) {
          asyncManager.async(new ConcurrentAsyncCall() {
              @Override
              public void callback() {
                  runnable.run();
              }
  
              @Override
              public boolean asPrimary() {
                  return true; // mail is primary business
              }
          });
      }
docs: ============