code: public IPromise getBooks( int id ) {
          Promise res = promise();
          // simulate blocking operation (e.g. database query)
          execInThreadPool( () -> new Book().title("Title "+id).id(""+id).author("kontraktor") ).
              then(res);
          return res;
      }
docs: curl -i -X GET http://localhost:8080/api/books/234234