diff --git a/staticlibs/device/com/android/net/module/util/BpfMap.java b/staticlibs/device/com/android/net/module/util/BpfMap.java
index 9df2b03..d45cace 100644
--- a/staticlibs/device/com/android/net/module/util/BpfMap.java
+++ b/staticlibs/device/com/android/net/module/util/BpfMap.java
@@ -194,9 +194,11 @@
     }
 
     private K getNextKeyInternal(@Nullable K key) throws ErrnoException {
-        final byte[] rawKey = getNextRawKey(
-                key == null ? null : key.writeToBytes());
-        if (rawKey == null) return null;
+        byte[] rawKey = new byte[mKeySize];
+
+        if (!nativeGetNextMapKey(mMapFd.getFd(),
+                                 key == null ? null : key.writeToBytes(),
+                                 rawKey)) return null;
 
         final ByteBuffer buffer = ByteBuffer.wrap(rawKey);
         buffer.order(ByteOrder.nativeOrder());
@@ -215,13 +217,6 @@
         return getNextKeyInternal(key);
     }
 
-    private byte[] getNextRawKey(@Nullable final byte[] key) throws ErrnoException {
-        byte[] nextKey = new byte[mKeySize];
-        if (nativeGetNextMapKey(mMapFd.getFd(), key, nextKey)) return nextKey;
-
-        return null;
-    }
-
     /** Get the first key of eBpf map. */
     @Override
     public K getFirstKey() throws ErrnoException {
@@ -233,30 +228,23 @@
     public boolean containsKey(@NonNull K key) throws ErrnoException {
         Objects.requireNonNull(key);
 
-        final byte[] rawValue = getRawValue(key.writeToBytes());
-        return rawValue != null;
+        byte[] rawValue = new byte[mValueSize];
+        return nativeFindMapEntry(mMapFd.getFd(), key.writeToBytes(), rawValue);
     }
 
     /** Retrieve a value from the map. Return null if there is no such key. */
     @Override
     public V getValue(@NonNull K key) throws ErrnoException {
         Objects.requireNonNull(key);
-        final byte[] rawValue = getRawValue(key.writeToBytes());
 
-        if (rawValue == null) return null;
+        byte[] rawValue = new byte[mValueSize];
+        if (!nativeFindMapEntry(mMapFd.getFd(), key.writeToBytes(), rawValue)) return null;
 
         final ByteBuffer buffer = ByteBuffer.wrap(rawValue);
         buffer.order(ByteOrder.nativeOrder());
         return Struct.parse(mValueClass, buffer);
     }
 
-    private byte[] getRawValue(final byte[] key) throws ErrnoException {
-        byte[] value = new byte[mValueSize];
-        if (nativeFindMapEntry(mMapFd.getFd(), key, value)) return value;
-
-        return null;
-    }
-
     /**
      * Iterate through the map and handle each key -> value retrieved base on the given BiConsumer.
      * The given BiConsumer may to delete the passed-in entry, but is not allowed to perform any
diff --git a/staticlibs/device/com/android/net/module/util/DeviceConfigUtils.java b/staticlibs/device/com/android/net/module/util/DeviceConfigUtils.java
index 5edf1b9..caa2b05 100644
--- a/staticlibs/device/com/android/net/module/util/DeviceConfigUtils.java
+++ b/staticlibs/device/com/android/net/module/util/DeviceConfigUtils.java
@@ -207,8 +207,9 @@
      *                       null.
      * @return true if this feature is enabled, or false if disabled.
      */
-    public static boolean isFeatureEnabled(@NonNull Context context, @NonNull String namespace,
-            @NonNull String name, @NonNull String moduleName, boolean defaultEnabled) {
+    public static boolean isTetheringFeatureEnabled(@NonNull Context context,
+            @NonNull String namespace, @NonNull String name, @NonNull String moduleName,
+            boolean defaultEnabled) {
         // TODO: migrate callers to a non-generic isTetheringFeatureEnabled method.
         if (!TETHERING_MODULE_NAME.equals(moduleName)) {
             throw new IllegalArgumentException(
@@ -339,7 +340,7 @@
      * If the feature is enabled by default and disabled by flag push (kill switch), this method
      * should be used.
      * If the feature is disabled by default and enabled by flag push,
-     * {@link #isFeatureEnabled(Context, String, String, String, boolean)} should be used.
+     * {@link #isTetheringFeatureEnabled} should be used.
      *
      * @param name The name of the property to look up.
      * @return true if this feature is enabled, or false if disabled.
diff --git a/staticlibs/device/com/android/net/module/util/FeatureVersions.java b/staticlibs/device/com/android/net/module/util/FeatureVersions.java
index 4986a58..149756c 100644
--- a/staticlibs/device/com/android/net/module/util/FeatureVersions.java
+++ b/staticlibs/device/com/android/net/module/util/FeatureVersions.java
@@ -22,13 +22,24 @@
  * @hide
  */
 public class FeatureVersions {
-    public static final long MODULE_MASK = 0xFF00_000000000L;
-    public static final long VERSION_MASK = 0x0000_FFFFFFFFFL;
-    public static final long CONNECTIVITY_MODULE_ID = 0x0100_000000000L;
-    public static final long NETWORK_STACK_MODULE_ID = 0x0200_000000000L;
+    /**
+     * This constant is used to do bitwise shift operation to create module ids.
+     * The module version is composed with 9 digits which is placed in the lower 36 bits.
+     */
+    private static final int MODULE_SHIFT = 36;
+    /**
+     * The bitmask to do bitwise-and(i.e. {@code &}) operation to get the module id.
+     */
+    public static final long MODULE_MASK = 0xFF0_0000_0000L;
+    /**
+     * The bitmask to do bitwise-and(i.e. {@code &}) operation to get the module version.
+     */
+    public static final long VERSION_MASK = 0x00F_FFFF_FFFFL;
+    public static final long CONNECTIVITY_MODULE_ID = 0x01L << MODULE_SHIFT;
+    public static final long NETWORK_STACK_MODULE_ID = 0x02L << MODULE_SHIFT;
     // CLAT_ADDRESS_TRANSLATE is a feature of the network stack, which doesn't throw when system
     // try to add a NAT-T keepalive packet filter with v6 address, introduced in version
     // M-2023-Sept on July 3rd, 2023.
     public static final long FEATURE_CLAT_ADDRESS_TRANSLATE =
-            NETWORK_STACK_MODULE_ID + 340900000L;
+            NETWORK_STACK_MODULE_ID + 34_09_00_000L;
 }
diff --git a/staticlibs/native/bpf_headers/include/bpf/BpfMap.h b/staticlibs/native/bpf_headers/include/bpf/BpfMap.h
index 0ab2fda..847083e 100644
--- a/staticlibs/native/bpf_headers/include/bpf/BpfMap.h
+++ b/staticlibs/native/bpf_headers/include/bpf/BpfMap.h
@@ -239,12 +239,9 @@
 
     Result<bool> isEmpty() const {
         auto key = getFirstKey();
-        if (!key.ok()) {
-            // Return error code ENOENT means the map is empty
-            if (key.error().code() == ENOENT) return true;
-            return key.error();
-        }
-        return false;
+        if (key.ok()) return false;
+        if (key.error().code() == ENOENT) return true;
+        return key.error();
     }
 
   private:
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt b/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt
index 9fb025b..e23f999 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt
@@ -63,9 +63,6 @@
         assertEquals(0, CollectionUtils.indexOfSubArray(haystack, byteArrayOf()))
         assertEquals(-1, CollectionUtils.indexOfSubArray(byteArrayOf(), byteArrayOf(3, 2)))
         assertEquals(0, CollectionUtils.indexOfSubArray(byteArrayOf(), byteArrayOf()))
-        assertThrows(NullPointerException::class.java) {
-            CollectionUtils.indexOfSubArray(haystack, null)
-        }
     }
 
     @Test
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/DeviceConfigUtilsTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/DeviceConfigUtilsTest.java
index cc17f9f..e80fa80 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/DeviceConfigUtilsTest.java
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/DeviceConfigUtilsTest.java
@@ -233,7 +233,7 @@
                 eq(TEST_EXPERIMENT_FLAG)));
         assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
     }
 
@@ -243,9 +243,9 @@
                 eq(TEST_EXPERIMENT_FLAG)));
         assertFalse(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG));
-        assertFalse(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertFalse(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, true /* defaultEnabled */));
     }
 
@@ -258,7 +258,7 @@
                 eq(TEST_EXPERIMENT_FLAG)));
         assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
 
         // Feature should be disabled by flag value "999999999".
@@ -266,7 +266,7 @@
                 eq(TEST_EXPERIMENT_FLAG)));
         assertFalse(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG));
-        assertFalse(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertFalse(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
 
         // Follow defaultEnabled if the flag is not set
@@ -276,9 +276,9 @@
                 TEST_EXPERIMENT_FLAG, false /* defaultEnabled */));
         assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, true /* defaultEnabled */));
-        assertFalse(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertFalse(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, true /* defaultEnabled */));
     }
 
@@ -293,14 +293,14 @@
 
         assertFalse(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG));
-        assertFalse(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertFalse(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, true /* defaultEnabled */));
 
         doReturn(TEST_FLAG_VALUE_STRING).when(() -> DeviceConfig.getProperty(eq(TEST_NAME_SPACE),
                 eq(TEST_EXPERIMENT_FLAG)));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
     }
 
@@ -323,9 +323,9 @@
     public void testFeatureIsEnabledCaching_APEX() throws Exception {
         doReturn(TEST_FLAG_VALUE_STRING).when(() -> DeviceConfig.getProperty(eq(TEST_NAME_SPACE),
                 eq(TEST_EXPERIMENT_FLAG)));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
-        assertTrue(DeviceConfigUtils.isFeatureEnabled(mContext, TEST_NAME_SPACE,
+        assertTrue(DeviceConfigUtils.isTetheringFeatureEnabled(mContext, TEST_NAME_SPACE,
                 TEST_EXPERIMENT_FLAG, TEST_APEX_NAME, false /* defaultEnabled */));
 
         // Package info is only queried once
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/FakeDns.kt b/staticlibs/testutils/devicetests/com/android/testutils/FakeDns.kt
index 825d748..1f82a35 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/FakeDns.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/FakeDns.kt
@@ -81,9 +81,9 @@
         var type = if (posType != -1) it.arguments[posType] as Int else TYPE_UNSPECIFIED
         val answer = getAnswer(hostname, type)
 
-        if (!answer?.addresses.isNullOrEmpty()) {
+        if (answer != null && !answer.addresses.isNullOrEmpty()) {
             Handler(Looper.getMainLooper()).post({ executor.execute({
-                    callback.onAnswer(answer?.addresses, 0); }) })
+                    callback.onAnswer(answer.addresses, 0); }) })
         }
     }
 
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt b/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt
index da3508d..d50f78a 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt
@@ -48,8 +48,8 @@
     private val natMap = NatMap()
     private val binder = Binder()
 
-    private val cm = context.getSystemService(ConnectivityManager::class.java)
-    private val tnm = context.getSystemService(TestNetworkManager::class.java)
+    private val cm = context.getSystemService(ConnectivityManager::class.java)!!
+    private val tnm = context.getSystemService(TestNetworkManager::class.java)!!
 
     // Create test networks.
     private val internalIface = tnm.createTunInterface(listOf(internalAddr))
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/TestNetworkTracker.kt b/staticlibs/testutils/devicetests/com/android/testutils/TestNetworkTracker.kt
index b743b6c..84fb47b 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/TestNetworkTracker.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/TestNetworkTracker.kt
@@ -91,7 +91,7 @@
     lp: LinkProperties?,
     setupTimeoutMs: Long = 10_000L
 ): TestNetworkTracker {
-    val tnm = context.getSystemService(TestNetworkManager::class.java)
+    val tnm = context.getSystemService(TestNetworkManager::class.java)!!
     val iface = if (isAtLeastS()) tnm.createTunInterface(linkAddrs)
     else tnm.createTunInterface(linkAddrs.toTypedArray())
     val lpWithIface = if (lp == null) null else LinkProperties(lp).apply {
@@ -112,7 +112,7 @@
     val lp: LinkProperties?,
     setupTimeoutMs: Long
 ) : TestableNetworkCallback.HasNetwork {
-    private val cm = context.getSystemService(ConnectivityManager::class.java)
+    private val cm = context.getSystemService(ConnectivityManager::class.java)!!
     private val binder = Binder()
 
     private val networkCallback: NetworkCallback