Clarify licensing through REUSE annotations.

 - Manual: GFDL-1.3-or-later
 - Library: LGPL-3.0-or-later
 - Examples: GPL-3.0-or-later

Change-Id: I1d1bfede7ba51c4043f8d7e572aa88b42cc8bacf
diff --git a/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/ByteStringTest.java b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/ByteStringTest.java
index a5fa2b4..1d3d84d 100644
--- a/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/ByteStringTest.java
+++ b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/ByteStringTest.java
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: © 2021 Matthias Andreas Benkard <code@mail.matthias.benkard.de>
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
 package eu.mulk.jgvariant.ostree;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;