Ensure nullness correctness using Checker Framework.

Change-Id: Ie5a7749194313664a206e44597091a62afca9bdb
diff --git a/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java
index 5c1dd79..d8ad271 100644
--- a/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java
+++ b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java
@@ -17,6 +17,7 @@
 import org.junit.jupiter.api.Test;
 
 @TestWithResources
+@SuppressWarnings("initialization.field.uninitialized")
 class OstreeDecoderTest {
 
   @GivenBinaryResource("/ostree/summary")