a$)$ Identify the pattern present in the code and name the roles of each class in the code. b$)$ Draw a class diagram connecting the classes. c$)$ Briefly describe two scenarios when you want to use this design pattern.

AA$.$java

public interface AA $\{$

void foo$1($SO so$)$;

void foo$2($SE se$)$;

void foo$3($CO co$)$;

$\}$

App.java

public class App $\{$

public static void main$($String$[]$ args$)\{$

UN co $=$ new CO$($

new SE$($new SO$(),$ new SO$(),$ new SO$()),$

new SE$($new SO$(),$ new SO$(),$ new SO$())$

$)$;

co$.$xx$($new BB$())$;

co$.$xx$($new DD$())$;

co$.$xx$($new CC$())$;

$\}$

$\}$

BB$.$java

public class BB implements AA $\{$

@Override

public void foo$1($SO so$)\{$

System.out.println$("$Greetings so$")$;

$\}$

@Override

public void foo$2($SE se$)\{$

$//$ Do nothing

$\}$

@Override

public void foo$3($CO co$)\{$

$//$ Do nothing

$\}$

$\}$

CC$.$java

@Override

public void foo$1($SO so$)\{$

$//$ Do nothing

$\}$

@Override

public void foo$2($SE se$)\{$

$//$ Do nothing

$\}$

@Override

public void foo$3($CO co$)\{$

System.out.println$("$Good to see you co$")$;

$\}$

$\}$

CO$.$java

public class CO extends UN $\{$

public CO$($UN$...$ children$)\{$

super$($children$)$;

$\}$

@Override

public void xx$($AA aa$)\{$

aa$.$foo$3($this$)$;

super.xx$($aa$)$;

$\}$

@Override

public String toString$()\{$

return "commander";

$\}$

$\}$

DD$.$java

public class DD implements AA $\{$

@Override

public void foo$1($SO so$)\{$

$//$ Do nothing

$\}$

@Override

public void foo$2($SE se$)\{$

System.out.println$("$Hello se$")$;

$\}$

@Override

public void foo$3($CO co$)\{$

$//$ Do nothing

$\}$

$\}$

SE$.$java

public class SE extends UN $\{$

public SE$($UN$...$ children$)\{$

super$($children$)$;

$\}$

@Override

public void xx$($AA aa$)\{$

aa$.$foo$2($this$)$;

super.xx$($aa$)$;

$\}$

@Override

public String toString$()\{$

return "sergeant";

$\}$

$\}$

SO$.$java

public class SO extends UN $\{$

public SO$($UN$...$ children$)\{$

super$($children$)$;

$\}$

@Override

public void xx$($AA aa$)\{$

aa$.$foo$1($this$)$;

super.xx$($aa$)$;

$\}$

@Override

public String toString$()\{$

return "soldier";

$\}$

$\}$

UN$.$java

import java.util.Arrays;

public abstract class UN $\{$

private UN$[]$ children;

public UN$($UN$...$ children$)\{$

this.children $=$ children;

$\}$

public void xx$($AA aa$)\{$

Arrays.stream$($children$).$forEach$($child $->$ child.xx$($aa$))$;

$\}$

$\}$