Design and code a class MultipleThree th ahas the following properties:

$1-$ An integer member variable num that is a multiple of three at all times.

$2-$ A getter

$3-$ A setter that accepts an integer and sets num to that integer if it's a multiple of three, otherwise it sets it

to the next number that's multiple of three.

$4-$ A Default constructor that sets num to $0$

$5-$ A constructor that accepts an integer and sets num to that integer if it's a multiple of three, otherwise it sets it

to the next number that's multiple of three.

$6-$ A method toString that return the object as a string

$7-$ A method equals that accepts a MultipleThree Object and return true if the two objects are equal and false otherwise

$8-$ A method add that accepts an integer and return a MultipleThree object with num set to the sum of num and the input

$9-$ Overload the method add to accept a MultipleThree object abd return a MultipleThree object as the sum of the two.

$10-$ Write a tester class to test all methods and constructors of your class.