[json-node] Make JsonNode Serializable

json-node/src/main/java/io/avaje/json/node/JsonArray.java

@@ -13,6 +13,8 @@
  */
 public final class JsonArray implements JsonNode {
 
+  private static final long serialVersionUID = 1L;
+
   private static final JsonArray EMPTY = new JsonArray(Collections.emptyList());
 
   private final List<JsonNode> children;

json-node/src/main/java/io/avaje/json/node/JsonBoolean.java

@@ -4,6 +4,8 @@
 
 public final /*value*/ class JsonBoolean implements JsonNode {
 
+  private static final long serialVersionUID = 1L;
+
   private final boolean value;
 
   public static JsonBoolean of(boolean value) {

json-node/src/main/java/io/avaje/json/node/JsonDecimal.java

@@ -7,6 +7,8 @@
 
 public final /*value*/ class JsonDecimal implements JsonNumber {
 
+  private static final long serialVersionUID = 1L;
+
   private final BigDecimal value;
 
   public static JsonDecimal of(BigDecimal value) {

json-node/src/main/java/io/avaje/json/node/JsonDouble.java

@@ -7,6 +7,8 @@
 
 public final /*value*/ class JsonDouble implements JsonNumber {
 
+  private static final long serialVersionUID = 1L;
+
   private final double value;
 
   public static JsonDouble of(double value) {

json-node/src/main/java/io/avaje/json/node/JsonInteger.java

@@ -7,6 +7,8 @@
 
 public final /*value*/ class JsonInteger implements JsonNumber {
 
+  private static final long serialVersionUID = 1L;
+
   private final int value;
 
   public static JsonInteger of(int value) {

json-node/src/main/java/io/avaje/json/node/JsonLong.java

@@ -7,6 +7,8 @@
 
 public final /*value*/ class JsonLong implements JsonNumber {
 
+  private static final long serialVersionUID = 1L;
+
   private final long value;
 
   public static JsonLong of(long value) {

json-node/src/main/java/io/avaje/json/node/JsonNode.java

@@ -2,10 +2,12 @@
 
 import org.jspecify.annotations.Nullable;
 
+import java.io.Serializable;
+
 /**
  * Represents the core JSON types.
  */
-public /*sealed*/ interface JsonNode
+public /*sealed*/ interface JsonNode extends Serializable
   /*permits JsonArray, JsonObject, JsonBoolean, JsonString, JsonNumber*/ {
 
   /**

json-node/src/main/java/io/avaje/json/node/JsonObject.java

@@ -15,6 +15,7 @@
  */
 public final class JsonObject implements JsonNode {
 
+  private static final long serialVersionUID = 1L;
   private static final JsonObject EMPTY = new JsonObject(Collections.emptyMap());
   private static final Pattern PATH_PATTERN = Pattern.compile("\\.");
 

json-node/src/main/java/io/avaje/json/node/JsonString.java

@@ -4,6 +4,8 @@
 
 public final /*value*/ class JsonString implements JsonNode {
 
+  private static final long serialVersionUID = 1L;
+
   private final String value;
 
   public static JsonString of(String value) {

json-node/src/test/java/io/avaje/json/node/SerializeTest.java

@@ -0,0 +1,37 @@
+package io.avaje.json.node;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.*;
+import java.math.BigDecimal;
+import static org.assertj.core.api.Assertions.assertThat;
+
+class SerializeTest {
+
+  @Test
+  void test() throws IOException, ClassNotFoundException {
+
+    Boolean.valueOf(true);
+    final var source = JsonArray.create()
+      .add("foo")
+      .add(JsonObject.create()
+        .add("aStr", "a")
+        .add("aBool", true)
+        .add("aInt", 42)
+        .add("aLong", 420L)
+        .add("aDouble", JsonDouble.of(4204.3D))
+        .add("aDecimal", JsonDecimal.of(BigDecimal.TEN))
+      );
+
+    var baos = new ByteArrayOutputStream();
+    try (var oos = new ObjectOutputStream(baos)) {
+      oos.writeObject(source);
+    }
+
+    var ois = new ObjectInputStream(new ByteArrayInputStream(baos.toByteArray()));
+    var readO = ois.readObject();
+
+    assertThat(readO).isInstanceOf(JsonArray.class);
+    assertThat(readO).isEqualTo(source);
+  }
+}