Java Program. Please only answer if you understand the problem.

Consider the problem of finding the Greatest Common Divisor (GCD) of two positive integers a and b. It can be mathematically proved that if b<=a

GCD(a, b) = b, if (a mod b) = 0;

GCD(a, b) = GCD(b, a mod b), if (a mod b) != 0.

Write a recursive function called GCD with signature public static int GCD(int a, int b) that returns the greatest common divisor of two positive integers a and b with b <= a.

Write a java program to test your function.