POM: Apply Flatten Maven Plugin.

Change-Id: Ia17df13f08958a322e7fb20467e1666cd55dbe2b
diff --git a/.gitignore b/.gitignore
index 452b5a4..1995b90 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
 *~
+.flattened-pom.xml
 /.idea
 /target
 /jgvariant-*/target