Fix #316

release-notes/VERSION-2.x

@@ -18,6 +18,8 @@ NOTE: Jackson 3.x components rely on 2.x annotations; there are no separate
 
 #314: Add `JsonInclude.Value` convenience constants
  (contributed by @runeflobakk)
+#316: Make `JsonFormat.Features` java.io.Serializable
+ (requested by @tiger9800)
 
 2.20 (28-Aug-2025)
 

src/main/java/com/fasterxml/jackson/annotation/JsonFormat.java

@@ -381,7 +381,10 @@ public enum Feature {
      * @since 2.6
      */
     public static class Features
+        implements java.io.Serializable // @since 2.21
     {
+        private static final long serialVersionUID = 1L;
+
         private final int _enabled, _disabled;
 
         private final static Features EMPTY = new Features(0, 0);

src/main/java/com/fasterxml/jackson/annotation/JsonIncludeProperties.java

@@ -47,7 +47,8 @@
      *
      * @since 2.12
      */
-    public static class Value implements JacksonAnnotationValue<JsonIncludeProperties>, java.io.Serializable
+    public static class Value implements JacksonAnnotationValue<JsonIncludeProperties>,
+        java.io.Serializable
     {
         private static final long serialVersionUID = 1L;
 

src/test/java/com/fasterxml/jackson/annotation/AnnotationTestUtil.java

@@ -0,0 +1,43 @@
+package com.fasterxml.jackson.annotation;
+
+import static org.junit.jupiter.api.Assertions.fail;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.UncheckedIOException;
+
+abstract class AnnotationTestUtil {
+    /*
+    /**********************************************************
+    /* JDK ser/deser
+    /**********************************************************
+     */
+
+    public static byte[] jdkSerialize(Object o)
+    {
+        ByteArrayOutputStream bytes = new ByteArrayOutputStream(2000);
+        try (ObjectOutputStream obOut = new ObjectOutputStream(bytes)) {
+            obOut.writeObject(o);
+            obOut.close();
+            return bytes.toByteArray();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> T jdkDeserialize(byte[] raw)
+    {
+        try (ObjectInputStream objIn = new ObjectInputStream(new ByteArrayInputStream(raw))) {
+            return (T) objIn.readObject();
+        } catch (ClassNotFoundException e) {
+            fail("Missing class: "+e.getMessage());
+            return null;
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+}

src/test/java/com/fasterxml/jackson/annotation/JacksonInjectTest.java

@@ -5,6 +5,7 @@
 import static org.junit.jupiter.api.Assertions.*;
 
 public class JacksonInjectTest
+    extends AnnotationTestUtil
 {
     private final static class Bogus {
         @JacksonInject(value="inject", useInput=OptBoolean.FALSE,
@@ -47,6 +48,11 @@ public void testFromAnnotation() throws Exception
         assertFalse(v.equals(EMPTY));
         assertFalse(EMPTY.equals(v));
 
+        // Verify JDK serializability
+        byte[] b = jdkSerialize(v);
+        JacksonInject.Value v2 = jdkDeserialize(b);
+        assertEquals(v, v2);
+
         JacksonInject ann2 = Bogus.class.getField("vanilla").getAnnotation(JacksonInject.class);
         v = JacksonInject.Value.from(ann2);
         assertEquals(JacksonInject.Value.construct(null, null, null), v,

src/test/java/com/fasterxml/jackson/annotation/FormatTest.java → src/test/java/com/fasterxml/jackson/annotation/JsonFormatTest.java

@@ -11,7 +11,8 @@
  * Tests to verify that it is possibly to merge {@link JsonFormat.Value}
  * instances for overrides.
  */
-public class FormatTest
+public class JsonFormatTest
+    extends AnnotationTestUtil
 {
     private final JsonFormat.Value EMPTY = JsonFormat.Value.empty();
 
@@ -71,15 +72,22 @@ public void testToString() {
     @Test
     public void testFromAnnotation()
     {
+        // Trivial case first:
+        assertSame(EMPTY, JsonFormat.Value.from(null));
+
+        // then real one
         JsonFormat ann = Bogus.class.getAnnotation(JsonFormat.class);
         JsonFormat.Value v = JsonFormat.Value.from(ann);
         assertEquals("xyz", v.getPattern());
         assertEquals(JsonFormat.Shape.BOOLEAN, v.getShape());
         // note: since it's not valid, should not try access as real thing
         assertEquals("bogus", v.timeZoneAsString());
 
-        // also:
-        assertSame(EMPTY, JsonFormat.Value.from(null));
+        // [annotations#316]: let's also verify JDK serializability
+        byte[] b = jdkSerialize(v);
+        JsonFormat.Value v2 = jdkDeserialize(b);
+
+        assertEquals(v, v2);
     }
 
     @Test