diff --git a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Commit.java b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Commit.java
index 209827d..f14e758 100644
--- a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Commit.java
+++ b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Commit.java
@@ -4,9 +4,10 @@
 
 package eu.mulk.jgvariant.ostree;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import eu.mulk.jgvariant.core.Decoder;
 import java.nio.ByteOrder;
-import java.nio.charset.StandardCharsets;
 import java.util.List;
 
 /**
@@ -48,8 +49,7 @@
   public record RelatedObject(String ref, Checksum commitChecksum) {
 
     private static final Decoder<RelatedObject> DECODER =
-        Decoder.ofStructure(
-            RelatedObject.class, Decoder.ofString(StandardCharsets.UTF_8), Checksum.decoder());
+        Decoder.ofStructure(RelatedObject.class, Decoder.ofString(UTF_8), Checksum.decoder());
 
     public static Decoder<RelatedObject> decoder() {
       return DECODER;
@@ -62,8 +62,8 @@
           Metadata.decoder(),
           Checksum.decoder(),
           Decoder.ofArray(RelatedObject.decoder()),
-          Decoder.ofString(StandardCharsets.UTF_8),
-          Decoder.ofString(StandardCharsets.UTF_8),
+          Decoder.ofString(UTF_8),
+          Decoder.ofString(UTF_8),
           Decoder.ofLong().withByteOrder(ByteOrder.BIG_ENDIAN),
           Checksum.decoder(),
           Checksum.decoder());
diff --git a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/DirTree.java b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/DirTree.java
index dc38b1b..8ac9e67 100644
--- a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/DirTree.java
+++ b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/DirTree.java
@@ -4,8 +4,9 @@
 
 package eu.mulk.jgvariant.ostree;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import eu.mulk.jgvariant.core.Decoder;
-import java.nio.charset.StandardCharsets;
 import java.util.List;
 
 /**
@@ -34,8 +35,7 @@
   public record File(String name, Checksum checksum) {
 
     private static final Decoder<File> DECODER =
-        Decoder.ofStructure(
-            File.class, Decoder.ofString(StandardCharsets.UTF_8), Checksum.decoder());
+        Decoder.ofStructure(File.class, Decoder.ofString(UTF_8), Checksum.decoder());
 
     /**
      * Acquires a {@link Decoder} for the enclosing type.
@@ -58,10 +58,7 @@
 
     private static final Decoder<Directory> DECODER =
         Decoder.ofStructure(
-            Directory.class,
-            Decoder.ofString(StandardCharsets.UTF_8),
-            Checksum.decoder(),
-            Checksum.decoder());
+            Directory.class, Decoder.ofString(UTF_8), Checksum.decoder(), Checksum.decoder());
 
     /**
      * Acquires a {@link Decoder} for the enclosing type.
diff --git a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Metadata.java b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Metadata.java
index 6e1f820..62f0331 100644
--- a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Metadata.java
+++ b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Metadata.java
@@ -4,9 +4,10 @@
 
 package eu.mulk.jgvariant.ostree;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import eu.mulk.jgvariant.core.Decoder;
 import eu.mulk.jgvariant.core.Variant;
-import java.nio.charset.StandardCharsets;
 import java.util.Map;
 
 /**
@@ -19,8 +20,7 @@
 public record Metadata(Map<String, Variant> fields) {
 
   private static final Decoder<Metadata> DECODER =
-      Decoder.ofDictionary(Decoder.ofString(StandardCharsets.UTF_8), Decoder.ofVariant())
-          .map(Metadata::new);
+      Decoder.ofDictionary(Decoder.ofString(UTF_8), Decoder.ofVariant()).map(Metadata::new);
 
   /**
    * Acquires a {@link Decoder} for the enclosing type.
diff --git a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SignedDelta.java b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SignedDelta.java
index e1fcd53..827d5e4 100644
--- a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SignedDelta.java
+++ b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SignedDelta.java
@@ -4,11 +4,12 @@
 
 package eu.mulk.jgvariant.ostree;
 
+import static java.nio.charset.StandardCharsets.US_ASCII;
+
 import eu.mulk.jgvariant.core.Decoder;
 import eu.mulk.jgvariant.core.Variant;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
-import java.nio.charset.StandardCharsets;
 import java.util.Map;
 
 /**
@@ -31,7 +32,7 @@
           SignedDelta.class,
           Decoder.ofLong().withByteOrder(ByteOrder.BIG_ENDIAN),
           ByteString.decoder().map(SignedDelta::decodeSuperblock),
-          Decoder.ofDictionary(Decoder.ofString(StandardCharsets.US_ASCII), Decoder.ofVariant()));
+          Decoder.ofDictionary(Decoder.ofString(US_ASCII), Decoder.ofVariant()));
 
   private static DeltaSuperblock decodeSuperblock(ByteString byteString) {
     return DeltaSuperblock.decoder().decode(ByteBuffer.wrap(byteString.bytes()));
diff --git a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Summary.java b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Summary.java
index 150ab00..2b8096d 100644
--- a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Summary.java
+++ b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/Summary.java
@@ -4,9 +4,10 @@
 
 package eu.mulk.jgvariant.ostree;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import eu.mulk.jgvariant.core.Decoder;
 import java.nio.ByteOrder;
-import java.nio.charset.StandardCharsets;
 import java.util.List;
 
 /**
@@ -58,7 +59,7 @@
     }
 
     private static final Decoder<Entry> DECODER =
-        Decoder.ofStructure(Entry.class, Decoder.ofString(StandardCharsets.UTF_8), Value.decoder());
+        Decoder.ofStructure(Entry.class, Decoder.ofString(UTF_8), Value.decoder());
 
     /**
      * Acquires a {@link Decoder} for the enclosing type.
diff --git a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SummarySignature.java b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SummarySignature.java
index c878955..3c88759 100644
--- a/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SummarySignature.java
+++ b/jgvariant-ostree/src/main/java/eu/mulk/jgvariant/ostree/SummarySignature.java
@@ -4,9 +4,10 @@
 
 package eu.mulk.jgvariant.ostree;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import eu.mulk.jgvariant.core.Decoder;
 import eu.mulk.jgvariant.core.Variant;
-import java.nio.charset.StandardCharsets;
 import java.util.Map;
 
 /**
@@ -21,8 +22,7 @@
 public record SummarySignature(Map<String, Variant> signatures) {
 
   private static final Decoder<SummarySignature> DECODER =
-      Decoder.ofDictionary(Decoder.ofString(StandardCharsets.UTF_8), Decoder.ofVariant())
-          .map(SummarySignature::new);
+      Decoder.ofDictionary(Decoder.ofString(UTF_8), Decoder.ofVariant()).map(SummarySignature::new);
 
   /**
    * Acquires a {@link Decoder} for the enclosing type.
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 1d3d84d..cd21e3c 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
@@ -11,25 +11,25 @@
 class ByteStringTest {
 
   @Test
-  void testToModifiedBase64() {
+  void toModifiedBase64() {
     assertEquals("MciDXVydLGaHpQCRyFFC0bLYU_9Bap+4G07jB1RRDVI", testByteString1.modifiedBase64());
   }
 
   @Test
-  void testOfModifiedBase64() {
+  void ofModifiedBase64() {
     assertEquals(
         testByteString1,
         ByteString.ofModifiedBase64("MciDXVydLGaHpQCRyFFC0bLYU_9Bap+4G07jB1RRDVI"));
   }
 
   @Test
-  void testToHex() {
+  void toHex() {
     assertEquals(
         "31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52", testByteString1.hex());
   }
 
   @Test
-  void testOfHex() {
+  void ofHex() {
     assertEquals(
         testByteString1,
         ByteString.ofHex("31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52"));
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 d8ad271..bca8142 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
@@ -17,7 +17,12 @@
 import org.junit.jupiter.api.Test;
 
 @TestWithResources
-@SuppressWarnings("initialization.field.uninitialized")
+@SuppressWarnings({
+  "ImmutableListOf1",
+  "ImmutableMapOf1",
+  "initialization.field.uninitialized",
+  "NullAway"
+})
 class OstreeDecoderTest {
 
   @GivenBinaryResource("/ostree/summary")
@@ -42,7 +47,7 @@
   byte[] deltaPartPayloadBytes;
 
   @Test
-  void testSummaryDecoder() {
+  void summaryDecoder() {
     var decoder = Summary.decoder();
     var summary = decoder.decode(ByteBuffer.wrap(summaryBytes));
     assertAll(
@@ -65,35 +70,35 @@
   }
 
   @Test
-  void testCommitDecoder() {
+  void commitDecoder() {
     var decoder = Commit.decoder();
     var commit = decoder.decode(ByteBuffer.wrap(commitBytes));
     System.out.println(commit);
   }
 
   @Test
-  void testDirTreeDecoder() {
+  void dirTreeDecoder() {
     var decoder = DirTree.decoder();
     var dirTree = decoder.decode(ByteBuffer.wrap(dirTreeBytes));
     System.out.println(dirTree);
   }
 
   @Test
-  void testDirMetaDecoder() {
+  void dirMetaDecoder() {
     var decoder = DirMeta.decoder();
     var dirMeta = decoder.decode(ByteBuffer.wrap(dirMetaBytes));
     System.out.println(dirMeta);
   }
 
   @Test
-  void testSuperblockDecoder() {
+  void superblockDecoder() {
     var decoder = DeltaSuperblock.decoder();
     var deltaSuperblock = decoder.decode(ByteBuffer.wrap(deltaSuperblockBytes));
     System.out.println(deltaSuperblock);
   }
 
   @Test
-  void testPartPayloadDecoder() {
+  void partPayloadDecoder() {
     var superblockDecoder = DeltaSuperblock.decoder();
     var superblock = superblockDecoder.decode(ByteBuffer.wrap(deltaSuperblockBytes));