refactor dao

spring-boot-mvc/src/main/java/com/baeldung/springbootmvc/jsfapplication/model/TodoDao.java

@@ -22,9 +22,9 @@ public class TodoDao implements Dao<Todo> {
 
     @Override
     public Collection<Todo> getAll() {
-        return Collections.unmodifiableCollection(todoList.stream()
+        return todoList.stream()
             .filter(Objects::nonNull)
-            .collect(Collectors.toList()));
+            .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
     }
 
     @Override