Recursive String Concatenation

What is printed when the following code is executed?

public class CapConcat {
    public static String capConcat(String[] arr, int index) {
         if(index == arr.length) return "";
         return arr[index].toUpperCase() + capConcat(arr, index + 1);
    }
    public static void main(String[] args) {
         String[] words = {"java", "code"};
         System.out.println(capConcat(words, 0));
    }
}