diff --git a/SQ-2021-H6/answer.pdf b/SQ-2021-H6/answer.pdf
new file mode 100644
index 0000000..f40c4ac
Binary files /dev/null and b/SQ-2021-H6/answer.pdf differ
diff --git a/SQ-2021-H6/report.pdf b/SQ-2021-H6/report.pdf
new file mode 100644
index 0000000..6db5cee
Binary files /dev/null and b/SQ-2021-H6/report.pdf differ
diff --git a/SQ-2021-H6/src/test/java/org/usi/sq/util/CollectionUtilsTest.java b/SQ-2021-H6/src/test/java/org/usi/sq/util/CollectionUtilsTest.java
index 79c1313..eb4d7f4 100644
--- a/SQ-2021-H6/src/test/java/org/usi/sq/util/CollectionUtilsTest.java
+++ b/SQ-2021-H6/src/test/java/org/usi/sq/util/CollectionUtilsTest.java
@@ -16,6 +16,7 @@ public class CollectionUtilsTest {
         assertEquals(expected, target);
     }
 
+    @SafeVarargs
     private static <T> List<T> list(T... elements) {
         return Arrays.asList(elements);
     }