find the greatest common divisor of a list of numbers in csharp

main.cs
public static int GetGCD(List<int> nums)
{
    if (nums == null || nums.Count == 0)
        throw new ArgumentException("List cannot be null or empty.");

    int result = nums[0];
    for (int i = 1; i < nums.Count; i++)
    {
        result = GetGCD(result, nums[i]); 
        // uses overload below to get gcd of two numbers
    }
    return result;
}

private static int GetGCD(int a, int b)
{
    if (b == 0)
        return a;
    else
        return GetGCD(b, a % b);
}
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