since v10.0.34

After making your app configurable the plugins of your app may access the configuration via the injectable app object. This object provides access to the app storage holding the configuration of your app:

private App app;

public String getName() {
  return app.getConfig().getString("config_key_name");

For a complete example take a look at the Hello World Supervisor Top Header App which makes use of this feature to configure the displayed text.