import java.util.*;
import java.util.stream.*;

var names = List.of("Mark", "Ann", "Paul");

// *** before: ***
List<String> upper1 = names.stream()
        .map(String::toUpperCase)
        .collect(Collectors.toList());

// *** in version 16: ***
List<String> upper2 = names.stream()
        .map(String::toUpperCase)
        .toList();                      // shorter, and the list is unmodifiable

System.out.println(upper1);
System.out.println(upper2);
// upper2.add("X");                     // <- UnsupportedOperationException