```
final Function<Boolean, ? extends Class<Void>> functionCallback = (Boolean t) -> {
   if(t) {
     plugin.setIsInstalled(Boolean.TRUE);             
   }
   return Void.TYPE;
};

foo.install(plugin,functionCallback);

if(plugin.getIsInstalled().getValue())
  return "done";
else 
  return "not done";

```

I want to check `if(plugin.getIsInstalled().getValue())` once the callback has finished executing. How can I prevent execution of this if condition until callback has completed execution?