Merge Two Strings and Pick Distinct

Take 2 strings s1 and s2 including only letters from a to z. Return a new sorted string, the longest possible, containing distinct letters, - each taken only once - coming from s1 or s2.

Example:

a = "xyaabbbccccdefww"
b = "xxxxyyyyabklmopq"
longest(a, b) -> "abcdefklmopqwxy"

a = "abcdefghijklmnopqrstuvwxyz"
longest(a, a) -> "abcdefghijklmnopqrstuvwxyz" 

Code:

public class TwoToOne {
    
    public static String longest (String s1, String s2) {
        String s = s1 + s2;
        return s.chars()

        .distinct()

        .sorted()

        .collect(StringBuilder::new 

                , StringBuilder::appendCodePoint

                , StringBuilder::append)

        .toString();
    }
}