diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 07c9dc1..55b31f2 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -4374,7 +4374,7 @@
 
     /**
      * @return VPN information for accounting, or null if we can't retrieve all required
-     *         information, e.g underlying ifaces.
+     *         information, e.g primary underlying iface.
      */
     @Nullable
     private VpnInfo createVpnInfo(Vpn vpn) {
@@ -4386,24 +4386,17 @@
         // see VpnService.setUnderlyingNetworks()'s javadoc about how to interpret
         // the underlyingNetworks list.
         if (underlyingNetworks == null) {
-            NetworkAgentInfo defaultNai = getDefaultNetwork();
-            if (defaultNai != null) {
-                underlyingNetworks = new Network[] { defaultNai.network };
+            NetworkAgentInfo defaultNetwork = getDefaultNetwork();
+            if (defaultNetwork != null && defaultNetwork.linkProperties != null) {
+                info.primaryUnderlyingIface = getDefaultNetwork().linkProperties.getInterfaceName();
+            }
+        } else if (underlyingNetworks.length > 0) {
+            LinkProperties linkProperties = getLinkProperties(underlyingNetworks[0]);
+            if (linkProperties != null) {
+                info.primaryUnderlyingIface = linkProperties.getInterfaceName();
             }
         }
-        if (underlyingNetworks != null && underlyingNetworks.length > 0) {
-            List<String> interfaces = new ArrayList<>();
-            for (Network network : underlyingNetworks) {
-                LinkProperties lp = getLinkProperties(network);
-                if (lp != null && !TextUtils.isEmpty(lp.getInterfaceName())) {
-                    interfaces.add(lp.getInterfaceName());
-                }
-            }
-            if (!interfaces.isEmpty()) {
-                info.underlyingIfaces = interfaces.toArray(new String[interfaces.size()]);
-            }
-        }
-        return info.underlyingIfaces == null ? null : info;
+        return info.primaryUnderlyingIface == null ? null : info;
     }
 
     /**
diff --git a/tests/net/java/android/net/NetworkStatsTest.java b/tests/net/java/android/net/NetworkStatsTest.java
index c16a0f4..b5b0384 100644
--- a/tests/net/java/android/net/NetworkStatsTest.java
+++ b/tests/net/java/android/net/NetworkStatsTest.java
@@ -569,7 +569,7 @@
             .addValues(underlyingIface, tunUid, SET_FOREGROUND, TAG_NONE, METERED_NO, ROAMING_NO,
                     DEFAULT_NETWORK_NO, 0L, 0L, 0L, 0L, 0L);
 
-        delta.migrateTun(tunUid, tunIface, new String[] {underlyingIface});
+        assertTrue(delta.toString(), delta.migrateTun(tunUid, tunIface, underlyingIface));
         assertEquals(20, delta.size());
 
         // tunIface and TEST_IFACE entries are not changed.
@@ -650,7 +650,7 @@
             .addValues(underlyingIface, tunUid, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
                     DEFAULT_NETWORK_NO,  75500L, 37L, 130000L, 70L, 0L);
 
-        delta.migrateTun(tunUid, tunIface, new String[]{underlyingIface});
+        assertTrue(delta.migrateTun(tunUid, tunIface, underlyingIface));
         assertEquals(9, delta.size());
 
         // tunIface entries should not be changed.
@@ -813,37 +813,6 @@
     }
 
     @Test
-    public void testFilterDebugEntries() {
-        NetworkStats.Entry entry1 = new NetworkStats.Entry(
-                "test1", 10100, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
-                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
-
-        NetworkStats.Entry entry2 = new NetworkStats.Entry(
-                "test2", 10101, SET_DBG_VPN_IN, TAG_NONE, METERED_NO, ROAMING_NO,
-                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
-
-        NetworkStats.Entry entry3 = new NetworkStats.Entry(
-                "test2", 10101, SET_DEFAULT, TAG_NONE, METERED_NO, ROAMING_NO,
-                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
-
-        NetworkStats.Entry entry4 = new NetworkStats.Entry(
-                "test2", 10101, SET_DBG_VPN_OUT, TAG_NONE, METERED_NO, ROAMING_NO,
-                DEFAULT_NETWORK_NO, 50000L, 25L, 100000L, 50L, 0L);
-
-        NetworkStats stats = new NetworkStats(TEST_START, 4)
-                .addValues(entry1)
-                .addValues(entry2)
-                .addValues(entry3)
-                .addValues(entry4);
-
-        stats.filterDebugEntries();
-
-        assertEquals(2, stats.size());
-        assertEquals(entry1, stats.getValues(0, null));
-        assertEquals(entry3, stats.getValues(1, null));
-    }
-
-    @Test
     public void testApply464xlatAdjustments() {
         final String v4Iface = "v4-wlan0";
         final String baseIface = "wlan0";
diff --git a/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java b/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
index 31df9f3..f453f6e 100644
--- a/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
+++ b/tests/net/java/com/android/server/net/NetworkStatsServiceTest.java
@@ -56,11 +56,11 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.argThat;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -216,16 +216,11 @@
         expectNetworkStatsUidDetail(buildEmptyStats());
         expectSystemReady();
 
-        assertNull(mService.getTunAdjustedStats());
         mService.systemReady();
-        // Verify that system ready fetches realtime stats and initializes tun adjusted stats.
-        verify(mNetManager).getNetworkStatsUidDetail(UID_ALL, INTERFACES_ALL);
-        assertNotNull("failed to initialize TUN adjusted stats", mService.getTunAdjustedStats());
-        assertEquals(0, mService.getTunAdjustedStats().size());
-
         mSession = mService.openSession();
         assertNotNull("openSession() failed", mSession);
 
+
         // catch INetworkManagementEventObserver during systemReady()
         ArgumentCaptor<INetworkManagementEventObserver> networkObserver =
               ArgumentCaptor.forClass(INetworkManagementEventObserver.class);
@@ -738,13 +733,11 @@
 
         NetworkStats stats = mService.getDetailedUidStats(ifaceFilter);
 
-        // mNetManager#getNetworkStatsUidDetail(UID_ALL, INTERFACES_ALL) has following invocations:
-        // 1) NetworkStatsService#systemReady from #setUp.
-        // 2) mService#forceUpdateIfaces in the test above.
-        // 3) Finally, mService#getDetailedUidStats.
-        verify(mNetManager, times(3)).getNetworkStatsUidDetail(UID_ALL, INTERFACES_ALL);
-        assertTrue(ArrayUtils.contains(stats.getUniqueIfaces(), TEST_IFACE));
-        assertTrue(ArrayUtils.contains(stats.getUniqueIfaces(), stackedIface));
+        verify(mNetManager, times(1)).getNetworkStatsUidDetail(eq(UID_ALL), argThat(ifaces ->
+                ifaces != null && ifaces.length == 2
+                        && ArrayUtils.contains(ifaces, TEST_IFACE)
+                        && ArrayUtils.contains(ifaces, stackedIface)));
+
         assertEquals(2, stats.size());
         assertEquals(uidStats, stats.getValues(0, null));
         assertEquals(tetheredStats1, stats.getValues(1, null));
@@ -930,70 +923,11 @@
     }
 
     @Test
-    public void vpnRewriteTrafficThroughItself() throws Exception {
-        // WiFi network is connected and VPN is using WiFi (which has TEST_IFACE).
-        expectDefaultSettings();
-        NetworkState[] networkStates = new NetworkState[] {buildWifiState(), buildVpnState()};
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
-        expectNetworkStatsUidDetail(buildEmptyStats());
-        expectBandwidthControlCheck();
-
-        mService.forceUpdateIfaces(
-                new Network[] {WIFI_NETWORK, VPN_NETWORK},
-                vpnInfos,
-                networkStates,
-                getActiveIface(networkStates));
-        // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
-        // overhead per packet):
-        //
-        // 1000 bytes (100 packets) were sent, and 2000 bytes (200 packets) were received by UID_RED
-        // over VPN.
-        // 500 bytes (50 packets) were sent, and 1000 bytes (100 packets) were received by UID_BLUE
-        // over VPN.
-        //
-        // VPN UID rewrites packets read from TUN back to TUN, plus some of its own traffic
-        // (100 bytes).
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 5)
-                .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 2000L, 200L, 1000L, 100L, 1L)
-                .addValues(TUN_IFACE, UID_BLUE, SET_DEFAULT, TAG_NONE, 1000L, 100L, 500L, 50L, 1L)
-                // VPN rewrites all the packets read from TUN + 100 additional bytes of VPN's
-                // own traffic.
-                .addValues(TUN_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 0L, 0L, 1600L, 160L, 2L)
-                // VPN sent 1760 bytes over WiFi in foreground (SET_FOREGROUND) i.e. 1600
-                // bytes (160 packets) + 1 byte/packet overhead (=160 bytes).
-                .addValues(TEST_IFACE, UID_VPN, SET_FOREGROUND, TAG_NONE, 0L, 0L, 1760L, 176L, 1L)
-                // VPN received 3300 bytes over WiFi in background (SET_DEFAULT) i.e. 3000 bytes
-                // (300 packets) + 1 byte/packet encryption overhead (=300 bytes).
-                .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 3300L, 300L, 0L, 0L, 1L));
-
-        forcePollAndWaitForIdle();
-
-        // Verify increased TUN usage by UID_VPN does not get attributed to other apps.
-        NetworkStats tunStats =
-                mService.getDetailedUidStats(new String[] {TUN_IFACE});
-        assertValues(
-                tunStats, TUN_IFACE, UID_RED, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 2000L, 200L, 1000L, 100L, 1);
-        assertValues(
-                tunStats, TUN_IFACE, UID_BLUE, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 1000L, 100L, 500L, 50L, 1);
-        assertValues(
-                tunStats, TUN_IFACE, UID_VPN, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 0L, 0L, 1600L, 160L, 2);
-
-        // Verify correct attribution over WiFi.
-        assertUidTotal(sTemplateWifi, UID_RED, 2000L, 200L, 1000L, 100L, 1);
-        assertUidTotal(sTemplateWifi, UID_BLUE, 1000L, 100L, 500L, 50L, 1);
-        assertUidTotal(sTemplateWifi, UID_VPN, 300L, 0L, 260L, 26L, 2);
-    }
-
-    @Test
     public void vpnWithOneUnderlyingIface() throws Exception {
         // WiFi network is connected and VPN is using WiFi (which has TEST_IFACE).
         expectDefaultSettings();
         NetworkState[] networkStates = new NetworkState[] {buildWifiState(), buildVpnState()};
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
+        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(TEST_IFACE)};
         expectNetworkStatsUidDetail(buildEmptyStats());
         expectBandwidthControlCheck();
 
@@ -1004,74 +938,23 @@
                 getActiveIface(networkStates));
         // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
         // overhead per packet):
-        // 1000 bytes (100 packets) were sent, and 2000 bytes (200 packets) were received by UID_RED
-        // over VPN.
-        // 500 bytes (50 packets) were sent, and 1000 bytes (100 packets) were received by UID_BLUE
-        // over VPN.
-        // VPN sent 1650 bytes (150 packets), and received 3300 (300 packets) over WiFi.
-        // Of 1650 bytes sent over WiFi, expect 1000 bytes attributed to UID_RED, 500 bytes
-        // attributed to UID_BLUE, and 150 bytes attributed to UID_VPN.
-        // Of 3300 bytes received over WiFi, expect 2000 bytes attributed to UID_RED, 1000 bytes
-        // attributed to UID_BLUE, and 300 bytes attributed to UID_VPN.
+        // 1000 bytes (100 packets) were sent/received by UID_RED over VPN.
+        // 500 bytes (50 packets) were sent/received by UID_BLUE over VPN.
+        // VPN sent/received 1650 bytes (150 packets) over WiFi.
+        // Of 1650 bytes over WiFi, expect 1000 bytes attributed to UID_RED, 500 bytes attributed to
+        // UID_BLUE, and 150 bytes attributed to UID_VPN for both rx/tx traffic.
         incrementCurrentTime(HOUR_IN_MILLIS);
         expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 3)
-                .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 2000L, 200L, 1000L, 100L, 1L)
-                .addValues(TUN_IFACE, UID_BLUE, SET_DEFAULT, TAG_NONE, 1000L, 100L, 500L, 50L, 1L)
-                // VPN received 3300 bytes over WiFi in background (SET_DEFAULT).
-                .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 3300L, 300L, 0L, 0L, 1L)
-                // VPN sent 1650 bytes over WiFi in foreground (SET_FOREGROUND).
-                .addValues(TEST_IFACE, UID_VPN, SET_FOREGROUND, TAG_NONE, 0L, 0L, 1650L, 150L, 1L));
+                .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 1000L, 100L, 1000L, 100L, 1L)
+                .addValues(TUN_IFACE, UID_BLUE, SET_DEFAULT, TAG_NONE, 500L, 50L, 500L, 50L, 1L)
+                .addValues(
+                    TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 1650L, 150L, 1650L, 150L, 2L));
 
         forcePollAndWaitForIdle();
 
-        assertUidTotal(sTemplateWifi, UID_RED, 2000L, 200L, 1000L, 100L, 1);
-        assertUidTotal(sTemplateWifi, UID_BLUE, 1000L, 100L, 500L, 50L, 1);
-        assertUidTotal(sTemplateWifi, UID_VPN, 300L, 0L, 150L, 0L, 2);
-    }
-
-    @Test
-    public void vpnWithOneUnderlyingIfaceAndOwnTraffic() throws Exception {
-        // WiFi network is connected and VPN is using WiFi (which has TEST_IFACE).
-        expectDefaultSettings();
-        NetworkState[] networkStates = new NetworkState[] {buildWifiState(), buildVpnState()};
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
-        expectNetworkStatsUidDetail(buildEmptyStats());
-        expectBandwidthControlCheck();
-
-        mService.forceUpdateIfaces(
-                new Network[] {WIFI_NETWORK, VPN_NETWORK},
-                vpnInfos,
-                networkStates,
-                getActiveIface(networkStates));
-        // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
-        // overhead per packet):
-        // 1000 bytes (100 packets) were sent, and 2000 bytes (200 packets) were received by UID_RED
-        // over VPN.
-        // 500 bytes (50 packets) were sent, and 1000 bytes (100 packets) were received by UID_BLUE
-        // over VPN.
-        // Additionally, the VPN sends 6000 bytes (600 packets) of its own traffic into the tun
-        // interface (passing that traffic to the VPN endpoint), and receives 5000 bytes (500
-        // packets) from it. Including overhead that is 6600/5500 bytes.
-        // VPN sent 8250 bytes (750 packets), and received 8800 (800 packets) over WiFi.
-        // Of 8250 bytes sent over WiFi, expect 1000 bytes attributed to UID_RED, 500 bytes
-        // attributed to UID_BLUE, and 6750 bytes attributed to UID_VPN.
-        // Of 8800 bytes received over WiFi, expect 2000 bytes attributed to UID_RED, 1000 bytes
-        // attributed to UID_BLUE, and 5800 bytes attributed to UID_VPN.
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 3)
-                .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 2000L, 200L, 1000L, 100L, 1L)
-                .addValues(TUN_IFACE, UID_BLUE, SET_DEFAULT, TAG_NONE, 1000L, 100L, 500L, 50L, 1L)
-                .addValues(TUN_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 5000L, 500L, 6000L, 600L, 1L)
-                // VPN received 8800 bytes over WiFi in background (SET_DEFAULT).
-                .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 8800L, 800L, 0L, 0L, 1L)
-                // VPN sent 8250 bytes over WiFi in foreground (SET_FOREGROUND).
-                .addValues(TEST_IFACE, UID_VPN, SET_FOREGROUND, TAG_NONE, 0L, 0L, 8250L, 750L, 1L));
-
-        forcePollAndWaitForIdle();
-
-        assertUidTotal(sTemplateWifi, UID_RED, 2000L, 200L, 1000L, 100L, 1);
-        assertUidTotal(sTemplateWifi, UID_BLUE, 1000L, 100L, 500L, 50L, 1);
-        assertUidTotal(sTemplateWifi, UID_VPN, 5800L, 500L, 6750L, 600L, 2);
+        assertUidTotal(sTemplateWifi, UID_RED, 1000L, 100L, 1000L, 100L, 1);
+        assertUidTotal(sTemplateWifi, UID_BLUE, 500L, 50L, 500L, 50L, 1);
+        assertUidTotal(sTemplateWifi, UID_VPN, 150L, 0L, 150L, 0L, 2);
     }
 
     @Test
@@ -1079,7 +962,7 @@
         // WiFi network is connected and VPN is using WiFi (which has TEST_IFACE).
         expectDefaultSettings();
         NetworkState[] networkStates = new NetworkState[] {buildWifiState(), buildVpnState()};
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
+        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(TEST_IFACE)};
         expectNetworkStatsUidDetail(buildEmptyStats());
         expectBandwidthControlCheck();
 
@@ -1110,136 +993,6 @@
     }
 
     @Test
-    public void vpnWithTwoUnderlyingIfaces_packetDuplication() throws Exception {
-        // WiFi and Cell networks are connected and VPN is using WiFi (which has TEST_IFACE) and
-        // Cell (which has TEST_IFACE2) and has declared both of them in its underlying network set.
-        // Additionally, VPN is duplicating traffic across both WiFi and Cell.
-        expectDefaultSettings();
-        NetworkState[] networkStates =
-                new NetworkState[] {
-                    buildWifiState(), buildMobile4gState(TEST_IFACE2), buildVpnState()
-                };
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE, TEST_IFACE2})};
-        expectNetworkStatsUidDetail(buildEmptyStats());
-        expectBandwidthControlCheck();
-
-        mService.forceUpdateIfaces(
-                new Network[] {WIFI_NETWORK, VPN_NETWORK},
-                vpnInfos,
-                networkStates,
-                getActiveIface(networkStates));
-        // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
-        // overhead per packet):
-        // 1000 bytes (100 packets) were sent/received by UID_RED and UID_BLUE over VPN.
-        // VPN sent/received 4400 bytes (400 packets) over both WiFi and Cell (8800 bytes in total).
-        // Of 8800 bytes over WiFi/Cell, expect:
-        // - 500 bytes rx/tx each over WiFi/Cell attributed to both UID_RED and UID_BLUE.
-        // - 1200 bytes rx/tx each over WiFi/Cell for VPN_UID.
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 4)
-                .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 1000L, 100L, 1000L, 100L, 2L)
-                .addValues(TUN_IFACE, UID_BLUE, SET_DEFAULT, TAG_NONE, 1000L, 100L, 1000L, 100L, 2L)
-                .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 2200L, 200L, 2200L, 200L, 2L)
-                .addValues(
-                    TEST_IFACE2, UID_VPN, SET_DEFAULT, TAG_NONE, 2200L, 200L, 2200L, 200L, 2L));
-
-        forcePollAndWaitForIdle();
-
-        assertUidTotal(sTemplateWifi, UID_RED, 500L, 50L, 500L, 50L, 1);
-        assertUidTotal(sTemplateWifi, UID_BLUE, 500L, 50L, 500L, 50L, 1);
-        assertUidTotal(sTemplateWifi, UID_VPN, 1200L, 100L, 1200L, 100L, 2);
-
-        assertUidTotal(buildTemplateMobileWildcard(), UID_RED, 500L, 50L, 500L, 50L, 1);
-        assertUidTotal(buildTemplateMobileWildcard(), UID_BLUE, 500L, 50L, 500L, 50L, 1);
-        assertUidTotal(buildTemplateMobileWildcard(), UID_VPN, 1200L, 100L, 1200L, 100L, 2);
-    }
-
-    @Test
-    public void vpnWithTwoUnderlyingIfaces_splitTraffic() throws Exception {
-        // WiFi and Cell networks are connected and VPN is using WiFi (which has TEST_IFACE) and
-        // Cell (which has TEST_IFACE2) and has declared both of them in its underlying network set.
-        // Additionally, VPN is arbitrarily splitting traffic across WiFi and Cell.
-        expectDefaultSettings();
-        NetworkState[] networkStates =
-                new NetworkState[] {
-                    buildWifiState(), buildMobile4gState(TEST_IFACE2), buildVpnState()
-                };
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE, TEST_IFACE2})};
-        expectNetworkStatsUidDetail(buildEmptyStats());
-        expectBandwidthControlCheck();
-
-        mService.forceUpdateIfaces(
-                new Network[] {WIFI_NETWORK, VPN_NETWORK},
-                vpnInfos,
-                networkStates,
-                getActiveIface(networkStates));
-        // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
-        // overhead per packet):
-        // 1000 bytes (100 packets) were sent, and 500 bytes (50 packets) received by UID_RED over
-        // VPN.
-        // VPN sent 660 bytes (60 packets) over WiFi and 440 bytes (40 packets) over Cell.
-        // And, it received 330 bytes (30 packets) over WiFi and 220 bytes (20 packets) over Cell.
-        // For UID_RED, expect 600 bytes attributed over WiFi and 400 bytes over Cell for sent (tx)
-        // traffic. For received (rx) traffic, expect 300 bytes over WiFi and 200 bytes over Cell.
-        //
-        // For UID_VPN, expect 60 bytes attributed over WiFi and 40 bytes over Cell for tx traffic.
-        // And, 30 bytes over WiFi and 20 bytes over Cell for rx traffic.
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 3)
-              .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 500L, 50L, 1000L, 100L, 2L)
-              .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 330L, 30L, 660L, 60L, 1L)
-              .addValues(TEST_IFACE2, UID_VPN, SET_DEFAULT, TAG_NONE, 220L, 20L, 440L, 40L, 1L));
-
-        forcePollAndWaitForIdle();
-
-        assertUidTotal(sTemplateWifi, UID_RED, 300L, 30L, 600L, 60L, 1);
-        assertUidTotal(sTemplateWifi, UID_VPN, 30L, 0L, 60L, 0L, 1);
-
-        assertUidTotal(buildTemplateMobileWildcard(), UID_RED, 200L, 20L, 400L, 40L, 1);
-        assertUidTotal(buildTemplateMobileWildcard(), UID_VPN, 20L, 0L, 40L, 0L, 1);
-    }
-
-    @Test
-    public void vpnWithTwoUnderlyingIfaces_splitTrafficWithCompression() throws Exception {
-        // WiFi and Cell networks are connected and VPN is using WiFi (which has TEST_IFACE) and
-        // Cell (which has TEST_IFACE2) and has declared both of them in its underlying network set.
-        // Additionally, VPN is arbitrarily splitting compressed traffic across WiFi and Cell.
-        expectDefaultSettings();
-        NetworkState[] networkStates =
-                new NetworkState[] {
-                    buildWifiState(), buildMobile4gState(TEST_IFACE2), buildVpnState()
-                };
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE, TEST_IFACE2})};
-        expectNetworkStatsUidDetail(buildEmptyStats());
-        expectBandwidthControlCheck();
-
-        mService.forceUpdateIfaces(
-                new Network[] {WIFI_NETWORK, VPN_NETWORK},
-                vpnInfos,
-                networkStates,
-                getActiveIface(networkStates));
-        // create some traffic (assume 10 bytes of MTU for VPN interface:
-        // 1000 bytes (100 packets) were sent/received by UID_RED over VPN.
-        // VPN sent/received 600 bytes (60 packets) over WiFi and 200 bytes (20 packets) over Cell.
-        // For UID_RED, expect 600 bytes attributed over WiFi and 200 bytes over Cell for both
-        // rx/tx.
-        // UID_VPN gets nothing attributed to it (avoiding negative stats).
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 4)
-              .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 1000L, 100L, 1000L, 100L, 1L)
-              .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 600L, 60L, 600L, 60L, 0L)
-              .addValues(TEST_IFACE2, UID_VPN, SET_DEFAULT, TAG_NONE, 200L, 20L, 200L, 20L, 0L));
-
-        forcePollAndWaitForIdle();
-
-        assertUidTotal(sTemplateWifi, UID_RED, 600L, 60L, 600L, 60L, 0);
-        assertUidTotal(sTemplateWifi, UID_VPN, 0L, 0L, 0L, 0L, 0);
-
-        assertUidTotal(buildTemplateMobileWildcard(), UID_RED, 200L, 20L, 200L, 20L, 0);
-        assertUidTotal(buildTemplateMobileWildcard(), UID_VPN, 0L, 0L, 0L, 0L, 0);
-    }
-
-    @Test
     public void vpnWithIncorrectUnderlyingIface() throws Exception {
         // WiFi and Cell networks are connected and VPN is using Cell (which has TEST_IFACE2),
         // but has declared only WiFi (TEST_IFACE) in its underlying network set.
@@ -1248,7 +1001,7 @@
                 new NetworkState[] {
                     buildWifiState(), buildMobile4gState(TEST_IFACE2), buildVpnState()
                 };
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
+        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(TEST_IFACE)};
         expectNetworkStatsUidDetail(buildEmptyStats());
         expectBandwidthControlCheck();
 
@@ -1277,134 +1030,6 @@
     }
 
     @Test
-    public void recordSnapshot_migratesTunTrafficAndUpdatesTunAdjustedStats() throws Exception {
-        assertEquals(0, mService.getTunAdjustedStats().size());
-        // VPN using WiFi (TEST_IFACE).
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
-        expectBandwidthControlCheck();
-        // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
-        // overhead per packet):
-        // 1000 bytes (100 packets) were downloaded by UID_RED over VPN.
-        // VPN received 1100 bytes (100 packets) over WiFi.
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 2)
-              .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 1000L, 100L, 0L, 0L, 0L)
-              .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 1100L, 100L, 0L, 0L, 0L));
-
-        // this should lead to NSS#recordSnapshotLocked
-        mService.forceUpdateIfaces(
-                new Network[0], vpnInfos, new NetworkState[0], null /* activeIface */);
-
-        // Verify TUN adjusted stats have traffic migrated correctly.
-        // Of 1100 bytes VPN received over WiFi, expect 1000 bytes attributed to UID_RED and 100
-        // bytes attributed to UID_VPN.
-        NetworkStats tunAdjStats = mService.getTunAdjustedStats();
-        assertValues(
-                tunAdjStats, TEST_IFACE, UID_RED, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 1000L, 100L, 0L, 0L, 0);
-        assertValues(
-                tunAdjStats, TEST_IFACE, UID_VPN, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 100L, 0L, 0L, 0L, 0);
-    }
-
-    @Test
-    public void getDetailedUidStats_migratesTunTrafficAndUpdatesTunAdjustedStats()
-            throws Exception {
-        assertEquals(0, mService.getTunAdjustedStats().size());
-        // VPN using WiFi (TEST_IFACE).
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
-        expectBandwidthControlCheck();
-        mService.forceUpdateIfaces(
-                new Network[0], vpnInfos, new NetworkState[0], null /* activeIface */);
-        // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
-        // overhead per packet):
-        // 1000 bytes (100 packets) were downloaded by UID_RED over VPN.
-        // VPN received 1100 bytes (100 packets) over WiFi.
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 2)
-              .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 1000L, 100L, 0L, 0L, 0L)
-              .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 1100L, 100L, 0L, 0L, 0L));
-
-        mService.getDetailedUidStats(INTERFACES_ALL);
-
-        // Verify internally maintained TUN adjusted stats
-        NetworkStats tunAdjStats = mService.getTunAdjustedStats();
-        // Verify stats for TEST_IFACE (WiFi):
-        // Of 1100 bytes VPN received over WiFi, expect 1000 bytes attributed to UID_RED and 100
-        // bytes attributed to UID_VPN.
-        assertValues(
-                tunAdjStats, TEST_IFACE, UID_RED, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 1000L, 100L, 0L, 0L, 0);
-        assertValues(
-                tunAdjStats, TEST_IFACE, UID_VPN, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 100L, 0L, 0L, 0L, 0);
-        // Verify stats for TUN_IFACE; only UID_RED should have usage on it.
-        assertValues(
-                tunAdjStats, TUN_IFACE, UID_RED, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 1000L, 100L, 0L, 0L, 0);
-        assertValues(
-                tunAdjStats, TUN_IFACE, UID_VPN, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 0L, 0L, 0L, 0L, 0);
-
-        // lets assume that since last time, VPN received another 1100 bytes (same assumptions as
-        // before i.e. UID_RED downloaded another 1000 bytes).
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        // Note - NetworkStatsFactory returns counters that are monotonically increasing.
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 2)
-              .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 2000L, 200L, 0L, 0L, 0L)
-              .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 2200L, 200L, 0L, 0L, 0L));
-
-        mService.getDetailedUidStats(INTERFACES_ALL);
-
-        tunAdjStats = mService.getTunAdjustedStats();
-        // verify TEST_IFACE stats:
-        assertValues(
-                tunAdjStats, TEST_IFACE, UID_RED, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 2000L, 200L, 0L, 0L, 0);
-        assertValues(
-                tunAdjStats, TEST_IFACE, UID_VPN, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 200L, 0L, 0L, 0L, 0);
-        // verify TUN_IFACE stats:
-        assertValues(
-                tunAdjStats, TUN_IFACE, UID_RED, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 2000L, 200L, 0L, 0L, 0);
-        assertValues(
-                tunAdjStats, TUN_IFACE, UID_VPN, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 0L, 0L, 0L, 0L, 0);
-    }
-
-    @Test
-    public void getDetailedUidStats_returnsCorrectStatsWithVpnRunning() throws Exception {
-        // VPN using WiFi (TEST_IFACE).
-        VpnInfo[] vpnInfos = new VpnInfo[] {createVpnInfo(new String[] {TEST_IFACE})};
-        expectBandwidthControlCheck();
-        mService.forceUpdateIfaces(
-                new Network[0], vpnInfos, new NetworkState[0], null /* activeIface */);
-        // create some traffic (assume 10 bytes of MTU for VPN interface and 1 byte encryption
-        // overhead per packet):
-        // 1000 bytes (100 packets) were downloaded by UID_RED over VPN.
-        // VPN received 1100 bytes (100 packets) over WiFi.
-        incrementCurrentTime(HOUR_IN_MILLIS);
-        expectNetworkStatsUidDetail(new NetworkStats(getElapsedRealtime(), 2)
-              .addValues(TUN_IFACE, UID_RED, SET_DEFAULT, TAG_NONE, 1000L, 100L, 0L, 0L, 0L)
-              .addValues(TEST_IFACE, UID_VPN, SET_DEFAULT, TAG_NONE, 1100L, 100L, 0L, 0L, 0L));
-
-        // Query realtime stats for TEST_IFACE.
-        NetworkStats queriedStats =
-                mService.getDetailedUidStats(new String[] {TEST_IFACE});
-
-        assertEquals(HOUR_IN_MILLIS, queriedStats.getElapsedRealtime());
-        // verify that returned stats are only for TEST_IFACE and VPN traffic is migrated correctly.
-        assertEquals(new String[] {TEST_IFACE}, queriedStats.getUniqueIfaces());
-        assertValues(
-                queriedStats, TEST_IFACE, UID_RED, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 1000L, 100L, 0L, 0L, 0);
-        assertValues(
-                queriedStats, TEST_IFACE, UID_VPN, SET_ALL, TAG_NONE, METERED_ALL, ROAMING_ALL,
-                DEFAULT_NETWORK_ALL, 100L, 0L, 0L, 0L, 0);
-    }
-
-    @Test
     public void testRegisterUsageCallback() throws Exception {
         // pretend that wifi network comes online; service should ask about full
         // network state, and poll any existing interfaces before updating.
@@ -1752,11 +1377,11 @@
         return new NetworkState(info, prop, new NetworkCapabilities(), VPN_NETWORK, null, null);
     }
 
-    private static VpnInfo createVpnInfo(String[] underlyingIfaces) {
+    private static VpnInfo createVpnInfo(String underlyingIface) {
         VpnInfo info = new VpnInfo();
         info.ownerUid = UID_VPN;
         info.vpnIface = TUN_IFACE;
-        info.underlyingIfaces = underlyingIfaces;
+        info.primaryUnderlyingIface = underlyingIface;
         return info;
     }