[FSSDK-11986] upgrade Jackson serializer deprecated class

.github/workflows/java.yml

@@ -49,17 +49,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        jdk: [8, 9]
+        # github not support JVM 8 anymore
+        jdk: [11, 17]
         optimizely_default_parser: [GSON_CONFIG_PARSER, JACKSON_CONFIG_PARSER, JSON_CONFIG_PARSER, JSON_SIMPLE_CONFIG_PARSER]
     steps:
       - name: checkout
         uses: actions/checkout@v4
 
       - name: set up JDK ${{ matrix.jdk }}
-        uses: AdoptOpenJDK/install-jdk@v1
+        uses: actions/setup-java@v4
         with:
-          version: ${{ matrix.jdk }}
-          architecture: x64
+          java-version: ${{ matrix.jdk }}
+          distribution: 'temurin'
 
       - name: Grant execute permission for gradlew
         run: chmod +x gradlew

README.md

@@ -44,9 +44,9 @@ dependencies {
   compile 'com.optimizely.ab:core-api:{VERSION}'
   compile 'com.optimizely.ab:core-httpclient-impl:{VERSION}'
   // The SDK integrates with multiple JSON parsers, here we use Jackson.
-  compile 'com.fasterxml.jackson.core:jackson-core:2.7.1'
-  compile 'com.fasterxml.jackson.core:jackson-annotations:2.7.1'
-  compile 'com.fasterxml.jackson.core:jackson-databind:2.7.1'
+  compile 'com.fasterxml.jackson.core:jackson-core:2.13.5'
+  compile 'com.fasterxml.jackson.core:jackson-annotations:2.13.5'
+  compile 'com.fasterxml.jackson.core:jackson-databind:2.13.5'
 }
 ```
 

core-api/src/main/java/com/optimizely/ab/event/internal/serializer/JacksonSerializer.java

@@ -1,6 +1,6 @@
 /**
  *
- *    Copyright 2016-2017, 2019, Optimizely and contributors
+ *    Copyright 2016-2017, 2019, 2025 Optimizely and contributors
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -19,13 +19,41 @@
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.PropertyNamingStrategy;
 
 class JacksonSerializer implements Serializer {
 
-    private ObjectMapper mapper =
-        new ObjectMapper().setPropertyNamingStrategy(
-            PropertyNamingStrategy.SNAKE_CASE);
+    private ObjectMapper mapper = createMapper();
+
+    /**
+     * Creates an ObjectMapper with snake_case naming strategy.
+     * Supports both Jackson 2.12+ (PropertyNamingStrategies) and earlier versions (PropertyNamingStrategy).
+     * Uses reflection to avoid compile-time dependencies on either API.
+     */
+    static ObjectMapper createMapper() {
+        ObjectMapper objectMapper = new ObjectMapper();
+        Object namingStrategy = getSnakeCaseStrategy();
+        objectMapper.setPropertyNamingStrategy((com.fasterxml.jackson.databind.PropertyNamingStrategy) namingStrategy);
+        return objectMapper;
+    }
+
+    /**
+     * Gets the snake case naming strategy, supporting both Jackson 2.12+ and earlier versions.
+     */
+    private static Object getSnakeCaseStrategy() {
+        try {
+            // Try Jackson 2.12+ API first
+            Class<?> strategiesClass = Class.forName("com.fasterxml.jackson.databind.PropertyNamingStrategies");
+            return strategiesClass.getField("SNAKE_CASE").get(null);
+        } catch (ClassNotFoundException | NoSuchFieldException | IllegalAccessException e) {
+            try {
+                // Fall back to Jackson 2.11 and earlier (deprecated but compatible)
+                Class<?> strategyClass = Class.forName("com.fasterxml.jackson.databind.PropertyNamingStrategy");
+                return strategyClass.getField("SNAKE_CASE").get(null);
+            } catch (ClassNotFoundException | NoSuchFieldException | IllegalAccessException ex) {
+                throw new RuntimeException("Unable to find snake_case naming strategy in Jackson", ex);
+            }
+        }
+    }
 
     public <T> String serialize(T payload) {
         mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

core-api/src/test/java/com/optimizely/ab/event/internal/serializer/JacksonSerializerTest.java

@@ -18,7 +18,6 @@
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 
-import com.fasterxml.jackson.databind.PropertyNamingStrategy;
 import com.optimizely.ab.event.internal.payload.EventBatch;
 
 import org.junit.Test;
@@ -36,14 +35,34 @@
 
 import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertNotNull;
 
 public class JacksonSerializerTest {
 
     private JacksonSerializer serializer = new JacksonSerializer();
-    private ObjectMapper mapper =
-        new ObjectMapper().setPropertyNamingStrategy(
-            PropertyNamingStrategy.SNAKE_CASE);
+    private ObjectMapper mapper = JacksonSerializer.createMapper();
 
+    @Test
+    public void createMapperSucceeds() {
+        // Verify that createMapper() successfully creates an ObjectMapper with snake_case naming
+        // This tests that the reflection logic works for the current Jackson version
+        ObjectMapper testMapper = JacksonSerializer.createMapper();
+        assertNotNull("Mapper should be created successfully", testMapper);
+
+        // Verify snake_case naming by serializing a simple object
+        class TestObject {
+            @SuppressWarnings("unused")
+            public String getMyFieldName() { return "test"; }
+        }
+
+        try {
+            String json = testMapper.writeValueAsString(new TestObject());
+            assertTrue("Should use snake_case naming", json.contains("my_field_name"));
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to serialize with snake_case naming", e);
+        }
+    }
 
     @Test
     public void serializeImpression() throws IOException {

java-quickstart/build.gradle

@@ -4,7 +4,11 @@ dependencies {
     implementation project(':core-api')
     implementation project(':core-httpclient-impl')
 
-    implementation group: 'com.google.code.gson', name: 'gson', version: gsonVersion
+    // implementation group: 'com.google.code.gson', name: 'gson', version: gsonVersion
+    implementation 'com.fasterxml.jackson.core:jackson-core:2.17.0'
+    implementation 'com.fasterxml.jackson.core:jackson-annotations:2.17.0'
+    implementation 'com.fasterxml.jackson.core:jackson-databind:2.17.0'
+
     implementation group: 'org.apache.httpcomponents', name: 'httpclient', version: httpClientVersion
     implementation group: 'org.apache.logging.log4j', name: 'log4j-api', version: log4jVersion
     implementation group: 'org.apache.logging.log4j', name: 'log4j-core', version: log4jVersion