code: void configureClassesReloadable(String path) {
  
          try {
              // Set up reloading:
              Path classesPath = FileSystems.getDefault().getPath(path);
              classesUrl = classesPath.toUri().toURL();
          } catch (IOException e) {
              throw new RuntimeException("Error starting class reloader", e);
          }
      }
docs: Configures dynamic class reloading. This is most useful for development
  (rather than deployment). This typically reloads classes from the
  <code>target/classes/...</code> directory of your development project.
  <p/>
  NB This provides an efficient development workflow, allowing you to see
  code changes without having to redeploy. It also supports stateless
  webapp design because the entire classes classloader is replaced every
  time there is a change (so you'll lose stuff like static variable
  values).