How are these methods ambiguous? (one takes array, another takes varargs)

Question

How are these append() methods ambiguous?

public class Try_MultipleArguments {

    public static void main(String[] args) {

        int array1[] = new int[] {1, 2, 3};

        int array2[] = new int[] {4, 5, 6};

        append(array1, array2);

        append(array1, 4, 5, 6);

    }

    public static int[] append(int[] array1, int[] array2) {
        int[] ans = new int[array1.length + array2.length];
        for(int i=0; i<array1.length; ++i) {
            ans[i] = array1[i];
        }
        for(int i=0; i<array2.length; ++i) {
            ans[i+array1.length] = array2[i];
        }
        return ans;
    }

    public static int[] append(int[] array1, int ... array2) {
        return append(array1,array2);
    }
}

UPDATE

Varargs is equivalent to an array, but this is from inside of the method. From outside of the method it should not be equivalent to it.

UPDATE 2

I see now that I can pass an array to vararg. I didn't knew that. Was always workarounding this need. Hmmm.... Was this from the very beginning of java varargs?

Answer 1

From the docs:

The three periods after the final parameter's type indicate that the final argument may be passed as an array or as a sequence of arguments.

So it's ambiguous because array also maps to the varargs.

Answer 2

They have the same definition.

In fact, int ... array2 is equivalent to int[] array2.