What needs to be changed in Unity's Transform to implement IEnumerable<Transform> plus IList<Transform> GetChildren() method

Transform.cs

public sealed class Transform : IEnumerable, IEnumerable<Transform>
{
    private sealed class Enumerator : IEnumerator, IEnumerator<Transform>
    {

        private Transform outer;
        private int currentIndex = -1;
        object IEnumerator.Current
        {
            get
            {
                return this.outer.GetChild(this.currentIndex);
            }
        }
        Transform IEnumerator<Transform>.Current
        {
            get
            {
                return this.outer.GetChild(this.currentIndex);
            }
        }
        internal Enumerator(Transform outer)
        {
            this.outer = outer;
        }
        public bool MoveNext()
        {
            int childCount = this.outer.childCount;
            return ++this.currentIndex < childCount;
        }
        public void Reset()
        {
            this.currentIndex = -1;
        }

        public void Dispose()
        {

        }
    }
    IEnumerator<Transform> IEnumerable<Transform>.GetEnumerator()
    {
        return new Enumerator(this);
    }
    IEnumerator IEnumerable.GetEnumerator()
    {
        return new Enumerator(this);
    }
    public IList<Transform> GetChildren()
    {
        var childs = new Transform[childCount];
        for (int i = 0; i < childs.Length; i++)
        {
            childs[i] = GetChild(i);
        }
        return childs;
    }
}