OAK-11387: Extract ListUtils from CollectionUtils - add class Javadoc

Author: reschke

oak-commons/src/main/java/org/apache/jackrabbit/oak/commons/collections/ListUtils.java

@@ -28,6 +28,9 @@
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
+/**
+ * Utility methods for {@link java.util.List} conversions.
+ */
 public class ListUtils {
 
     private ListUtils() {