Java generics

MainApp.java

public class A {
   public A() {
      MainApp.decorateMyClass(this);
   }
}

public class B {
   public B() {
      MainApp.decorateMyClass(this);
   }
}

public interface Decorator() {
   void decorate(A a);
   void decorate(B b);
}

public class MainApp {

   private Decorator decorator;
   private static MainApp mainApp;
   
   public MainApp() {
      mainApp = this;
      decorato = getConcreteFromSomewhere();
   }
   
   public static <T> void decorateMyClass(Class<T> clazz) {
      decorator.decorate(clazz);
   }

}