in java, without using streams please solve $.$You are designing a directory structure for a file system. Each directory can contain

files and subdirectories. Write a recursive function calculateTotalSize that takes a

Directory object as input and returns the total size $($in bytes$)$ of all files within the

directory and its subdirectories.

The Directory and File classes are defined as follows:

$1$ class Directory $\{$

$2$ private String name ;

$3$ private List $<$ File $>$ files ;

$4$ private List $<$ Directory $>$ subdirectories ;

$5$

$6$ public List $<$ File $>$ getFiles $()\{$

$7$ return files ;

$8\}$

$9$

$10$ public List $<$ Directory $>$ getSubdirectories $()\{$

$11$ return subdirectories ;

$12\}$

$13\}$

$14$

$15$ class File $\{$

$16$ private String name ;

$17$ private int size ; $//$ Size in bytes

$18$

$19$ public int getSize $()\{$

$20$ return size ;

$21\}$

$22\}$