diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9c424663..dd246f5c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Optimizely Android X SDK Changelog
 
+## 5.2.1
+May 29, 2026
+
+### Fixes
+
+- Upgrade dependency to [Java SDK 4.4.2](https://github.com/optimizely/java-sdk/releases/tag/v4.4.2)
+  - Block ODP identify event for single identifier
+
 ## 5.2.0
 May 8, 2026
 
diff --git a/README.md b/README.md
index 78ee9b48..de01f853 100644
--- a/README.md
+++ b/README.md
@@ -32,7 +32,7 @@ repositories {
 }
 
 dependencies {
-	implementation 'com.optimizely.ab:android-sdk:5.2.0'
+	implementation 'com.optimizely.ab:android-sdk:5.2.1'
 }
 ```
 
diff --git a/android-sdk/src/androidTest/java/com/optimizely/ab/android/sdk/ODPIntegrationTest.java b/android-sdk/src/androidTest/java/com/optimizely/ab/android/sdk/ODPIntegrationTest.java
index b9c37f3c..ab2f2ede 100644
--- a/android-sdk/src/androidTest/java/com/optimizely/ab/android/sdk/ODPIntegrationTest.java
+++ b/android-sdk/src/androidTest/java/com/optimizely/ab/android/sdk/ODPIntegrationTest.java
@@ -118,7 +118,7 @@ public void identifyOdpEventSentWhenUserContextCreated() throws InterruptedExcep
         verify(odpApiManager, times(1)).sendEvents(eq("p-1"), eq("h-1/v3/events"), captor.capture());
         String eventStr = captor.getValue();
 
-        // 2 events (client_initialized, identified) will be batched in a single sendEvents() call.
+        // 2 events batched: client_initialized + identified (identified sent because there are 2 identifiers: vuid + fs_user_id).
         JsonArray jsonArray = JsonParser.parseString(eventStr).getAsJsonArray();
         assertEquals(jsonArray.size(), 2);
 
@@ -146,7 +146,7 @@ public void identifyOdpEventSentWhenUserContextCreated() throws InterruptedExcep
     }
 
     @Test
-    public void identifyOdpEventSentWhenVuidUserContextCreated() throws InterruptedException {
+    public void identifyOdpEventNotSentWhenVuidUserContextCreated() throws InterruptedException {
         optimizelyClient.createUserContext();  // empty userId. vuid will be used.
 
         Thread.sleep(2000);  // wait for batch timeout (1sec)
@@ -155,25 +155,43 @@ public void identifyOdpEventSentWhenVuidUserContextCreated() throws InterruptedE
         verify(odpApiManager, times(1)).sendEvents(eq("p-1"), eq("h-1/v3/events"), captor.capture());
         String eventStr = captor.getValue();
 
-        // 2 events (client_initialized, identified) will be batched in a single sendEvents() call.
+        // only 1 event (client_initialized) since vuid-only context does not send identified event.
         JsonArray jsonArray = JsonParser.parseString(eventStr).getAsJsonArray();
-        assertEquals(jsonArray.size(), 2);
+        assertEquals(jsonArray.size(), 1);
 
         // "client_initialized" event (vuid only)
         JsonObject firstEvt = jsonArray.get(0).getAsJsonObject();
         JsonObject firstIdentifiers = firstEvt.get("identifiers").getAsJsonObject();
 
-        // "identified" event (vuid only)
-        JsonObject secondEvt = jsonArray.get(1).getAsJsonObject();
-        JsonObject secondIdentifiers = secondEvt.get("identifiers").getAsJsonObject();
-
         assertEquals(firstEvt.get("action").getAsString(), "client_initialized");
         assertEquals(firstIdentifiers.size(), 1);
         assertEquals(firstIdentifiers.get("vuid").getAsString(), testVuid);
+    }
 
-        assertEquals(secondEvt.get("action").getAsString(), "identified");
-        assertEquals(secondIdentifiers.size(), 1);
-        assertEquals(secondIdentifiers.get("vuid").getAsString(), testVuid);
+    @Test
+    public void identifyOdpEventNotSentWhenUserContextCreatedWithoutVuid() throws Exception {
+        // build a separate manager without vuid
+        ODPApiManager noVuidOdpApiManager = mock(ODPApiManager.class);
+        when(noVuidOdpApiManager.sendEvents(anyString(), anyString(), anyString())).thenReturn(200);
+
+        ODPEventManager noVuidEventManager = new ODPEventManager(noVuidOdpApiManager);
+        ODPSegmentManager noVuidSegmentManager = new ODPSegmentManager(noVuidOdpApiManager);
+
+        OptimizelyManager noVuidManager = OptimizelyManager.builder()
+            .withSDKKey(testSdkKey)
+            .withODPEventManager(noVuidEventManager)
+            .withODPSegmentManager(noVuidSegmentManager)
+            .build(context);
+
+        noVuidManager.initialize(context, odpDatafile);
+        OptimizelyClient noVuidClient = noVuidManager.getOptimizely();
+
+        noVuidClient.createUserContext(testUser);  // userId only, no vuid
+
+        Thread.sleep(2000);  // wait for batch timeout (1sec)
+
+        // no ODP events sent without vuid
+        verify(noVuidOdpApiManager, times(0)).sendEvents(anyString(), anyString(), anyString());
     }
 
     @Test
diff --git a/build.gradle b/build.gradle
index b8f8b720..1ae067c8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -97,7 +97,7 @@ ext {
     build_tools_version = "35.0.0"
     min_sdk_version = 21
     target_sdk_version = 35
-    java_core_ver = "4.4.0"
+    java_core_ver = "4.4.2"
     android_logger_ver = "1.3.6"
     jacksonversion= "2.11.2"
     annotations_ver = "1.2.0"
diff --git a/gradle.properties b/gradle.properties
index 70250523..309fbe0b 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -4,4 +4,4 @@ version = 0.0.0-SNAPSHOT
  
 android.enableJetifier=true
 android.useAndroidX=true
-org.gradle.jvmargs=-Xmx1g
+org.gradle.jvmargs=-Xmx4g