https://openjdk.java.net/ 
public interface java.awt.event.WindowFocusListener extends java.util.EventListener
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: java.awt.event.WindowFocusListener
  super_class: java.lang.Object
{
  public abstract void windowGainedFocus(java.awt.event.WindowEvent);
    descriptor: (Ljava/awt/event/WindowEvent;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
      Name  Flags
      e     

  public abstract void windowLostFocus(java.awt.event.WindowEvent);
    descriptor: (Ljava/awt/event/WindowEvent;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
      Name  Flags
      e     
}
SourceFile: "WindowFocusListener.java"