StringUtils.same opposite method to StringUtils.differ

This is pretty easy to do but I have seen this come up and was surprised to find that StringUtils didn't have a utility method.

The difference() method is described as doing the following:
Compares two Strings, and returns the portion where they differ.

What I am proposing is essentially the opposite of the difference method called same(). This method would compare two String and return a new String when they are the same.

This is essentially the implementation:

    public static String same(String str1, String str2) {
        if (str1 != null && StringUtils.equalsIgnoreCase(str1, str2)) {
            return new String(str1);
        }
        return null;
    }

StringUtils.same(null, null) = null
StringUtils.same("", "") = "";
StringUtils.same("123", "") = null
StringUtils.same("123", "123") = "123";

If there is already a way to do this using the apache lang library please point me in the right direction. Otherwise I would be more than happy to do the testing, coding and documentation for this.