I prepared a code using Java Generics to gain flexibility. I had one class named ImagePanel<T> extends Node<T> class that is also extends Panel (java.awt.Panel) class. The other class is PanelManager manages ImagePanel<T> class objects. I define both classes in the same file (GUI.java file - GUI class).
However, compiler gives this error :

"Note: spritesGUI/SpritesWindow.java uses unchecked or unsafe operations.Note: Recompile with -Xlint:unchecked for details."

The structure is :

class GUI {

  class ImagePanel<T> extends Node<T> { ...   }
  class PanelManager { ... public void ImagePanel getSleectedImagePanel(); }

As you see, I have "getSleectedImagePanel()" method which returns ImagePanel. I do not know how to transfer generic type T to PanelManager? Any help is appreciated.