Add a V->U restore allowlist/denylist

A package is eligible for V to U downgrade restore if either:
- The package has restoreAnyVersion set to false and is part of the V to U allowst
- The package has restoreAnyVersion set to true and is not part of the denylist

Bug : 324233962
Test: atest PerformUnifiedRestoreTaskTest
      Manual:check that a package with restoreanyversion=true
      is not restored if in the denylist,
      check that a package with restoreanyversion=false
      is restored if in the allowlist

Change-Id: Id1cf031c593730132ebe24ecab0ffc4a3f87920e
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index ec4d587..50adc40 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -12481,6 +12481,24 @@
         public static void setLocationProviderEnabled(ContentResolver cr,
                 String provider, boolean enabled) {
         }
+
+        /**
+         * List of system components that support restore in a  V-> U OS downgrade but do not have
+         * RestoreAnyVersion set to true. Value set before system restore.
+         * This setting is not B&Rd
+         * List is stored as a comma-separated string of package names e.g. "a,b,c"
+         * @hide
+         */
+        public static final String V_TO_U_RESTORE_ALLOWLIST = "v_to_u_restore_allowlist";
+
+        /**
+         * List of system components that have RestoreAnyVersion set to true but do not support
+         * restore in a  V-> U OS downgrade. Value set before system restore.
+         * This setting is not B&Rd
+         * List is stored as a comma-separated string of package names e.g. "a,b,c"
+         * @hide
+         */
+        public static final String V_TO_U_RESTORE_DENYLIST = "v_to_u_restore_denylist";
     }
 
     /**
diff --git a/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java b/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java
index b58187d..28cdc6d 100644
--- a/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java
+++ b/packages/SettingsProvider/test/src/android/provider/SettingsBackupTest.java
@@ -807,7 +807,9 @@
                  Settings.Secure.UI_TRANSLATION_ENABLED,
                  Settings.Secure.ACCESSIBILITY_DISPLAY_MAGNIFICATION_EDGE_HAPTIC_ENABLED,
                  Settings.Secure.DND_CONFIGS_MIGRATED,
-                 Settings.Secure.NAVIGATION_MODE_RESTORE);
+                 Settings.Secure.NAVIGATION_MODE_RESTORE,
+                 Settings.Secure.V_TO_U_RESTORE_ALLOWLIST,
+                 Settings.Secure.V_TO_U_RESTORE_DENYLIST);
 
     @Test
     public void systemSettingsBackedUpOrDenied() {
diff --git a/services/backup/flags.aconfig b/services/backup/flags.aconfig
index 71f2b9e..e9f959f 100644
--- a/services/backup/flags.aconfig
+++ b/services/backup/flags.aconfig
@@ -35,6 +35,15 @@
 }
 
 flag {
+    name: "enable_v_to_u_restore_for_system_components_in_allowlist"
+    namespace: "onboarding"
+    description: "Enables system components to opt in to support restore in V to U downgrade "
+            "scenario without opting in for restoreAnyVersion."
+    bug: "324233962"
+    is_fixed_read_only: true
+}
+
+flag {
     name: "enable_increase_datatypes_for_agent_logging"
     namespace: "onboarding"
     description: "Increase the number of a supported datatypes that an agent can define for its "
diff --git a/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java b/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java
index 9f0deea..6e98e68 100644
--- a/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java
+++ b/services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java
@@ -177,6 +177,10 @@
         return mHasMetadata;
     }
 
+    public int getSourceSdk() {
+        return mStoredSdkVersion;
+    }
+
     public Metadata getRestoredMetadata(String packageName) {
         if (mRestoredSignatures == null) {
             Slog.w(TAG, "getRestoredMetadata() before metadata read!");
diff --git a/services/backup/java/com/android/server/backup/restore/PerformUnifiedRestoreTask.java b/services/backup/java/com/android/server/backup/restore/PerformUnifiedRestoreTask.java
index d85dd87..e666442 100644
--- a/services/backup/java/com/android/server/backup/restore/PerformUnifiedRestoreTask.java
+++ b/services/backup/java/com/android/server/backup/restore/PerformUnifiedRestoreTask.java
@@ -44,6 +44,7 @@
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.pm.PackageManagerInternal;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.Message;
 import android.os.ParcelFileDescriptor;
@@ -51,6 +52,7 @@
 import android.os.RemoteException;
 import android.os.SystemClock;
 import android.os.UserHandle;
+import android.provider.Settings;
 import android.util.EventLog;
 import android.util.Slog;
 
@@ -82,6 +84,7 @@
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
@@ -158,6 +161,12 @@
     // When finished call listener
     private final OnTaskFinishedListener mListener;
 
+    // List of packages that support  V-> U downgrade but do not have RestoreAnyVersion set to true.
+    private List<String> mVToUAllowlist;
+
+    // List of packages that have RestoreAnyVersion set to true but do not support  V-> U downgrade.
+    private List<String> mVToUDenylist;
+
     // Key/value: bookkeeping about staged data and files for agent access
     private File mBackupDataName;
     private File mStageName;
@@ -172,7 +181,8 @@
     @VisibleForTesting
     PerformUnifiedRestoreTask(
             UserBackupManagerService backupManagerService,
-            TransportConnection transportConnection) {
+            TransportConnection transportConnection,
+            String vToUAllowlist, String vToUDenyList) {
         mListener = null;
         mAgentTimeoutParameters = null;
         mOperationStorage = null;
@@ -183,6 +193,8 @@
         mBackupEligibilityRules = null;
         this.backupManagerService = backupManagerService;
         mBackupManagerMonitorEventSender = new BackupManagerMonitorEventSender(/* monitor= */ null);
+        mVToUAllowlist = createVToUList(vToUAllowlist);
+        mVToUDenylist = createVToUList(vToUDenyList);
     }
 
     // This task can assume that the wakelock is properly held for it and doesn't have to worry
@@ -223,6 +235,18 @@
                         backupManagerService.getAgentTimeoutParameters(),
                         "Timeout parameters cannot be null");
         mBackupEligibilityRules = backupEligibilityRules;
+        mVToUAllowlist =
+            createVToUList(
+                Settings.Secure.getStringForUser(
+                    backupManagerService.getContext().getContentResolver(),
+                    Settings.Secure.V_TO_U_RESTORE_ALLOWLIST,
+                    mUserId));
+        mVToUDenylist =
+            createVToUList(
+                Settings.Secure.getStringForUser(
+                    backupManagerService.getContext().getContentResolver(),
+                    Settings.Secure.V_TO_U_RESTORE_DENYLIST,
+                    mUserId));
 
         if (targetPackage != null) {
             // Single package restore
@@ -636,60 +660,29 @@
                 // Data is from a "newer" version of the app than we have currently
                 // installed.  If the app has not declared that it is prepared to
                 // handle this case, we do not attempt the restore.
-                if ((mCurrentPackage.applicationInfo.flags
-                                & ApplicationInfo.FLAG_RESTORE_ANY_VERSION)
-                        == 0) {
-                    String message =
-                            "Source version "
-                                    + metaInfo.versionCode
-                                    + " > installed version "
-                                    + mCurrentPackage.getLongVersionCode();
-                    Slog.w(TAG, "Package " + pkgName + ": " + message);
-                    Bundle monitoringExtras =
-                            mBackupManagerMonitorEventSender.putMonitoringExtra(
-                                    null,
-                                    BackupManagerMonitor.EXTRA_LOG_RESTORE_VERSION,
-                                    metaInfo.versionCode);
-                    monitoringExtras =
-                            mBackupManagerMonitorEventSender.putMonitoringExtra(
-                                    monitoringExtras,
-                                    BackupManagerMonitor.EXTRA_LOG_RESTORE_ANYWAY,
-                                    false);
-                    monitoringExtras = addRestoreOperationTypeToEvent(monitoringExtras);
-                    mBackupManagerMonitorEventSender.monitorEvent(
-                            BackupManagerMonitor.LOG_EVENT_ID_RESTORE_VERSION_HIGHER,
-                            mCurrentPackage,
-                            BackupManagerMonitor.LOG_EVENT_CATEGORY_BACKUP_MANAGER_POLICY,
-                            monitoringExtras);
-                    EventLog.writeEvent(EventLogTags.RESTORE_AGENT_FAILURE, pkgName, message);
-                    nextState = UnifiedRestoreState.RUNNING_QUEUE;
-                    return;
-                } else {
-                    if (DEBUG) {
-                        Slog.v(
-                                TAG,
-                                "Source version "
-                                        + metaInfo.versionCode
-                                        + " > installed version "
-                                        + mCurrentPackage.getLongVersionCode()
-                                        + " but restoreAnyVersion");
+                if (mIsSystemRestore
+                    && isVToUDowngrade(mPmAgent.getSourceSdk(), android.os.Build.VERSION.SDK_INT)) {
+                    if (isPackageEligibleForVToURestore(mCurrentPackage)) {
+                        Slog.i(TAG, "Package " + pkgName
+                                + " is eligible for V to U downgrade scenario");
+                    } else {
+                        String message = "Package not eligible for V to U downgrade scenario";
+                        Slog.i(TAG, pkgName + " : " + message);
+                        EventLog.writeEvent(EventLogTags.RESTORE_AGENT_FAILURE, pkgName, message);
+                        nextState = UnifiedRestoreState.RUNNING_QUEUE;
+                        return;
                     }
-                    Bundle monitoringExtras =
-                            mBackupManagerMonitorEventSender.putMonitoringExtra(
-                                    null,
-                                    BackupManagerMonitor.EXTRA_LOG_RESTORE_VERSION,
-                                    metaInfo.versionCode);
-                    monitoringExtras =
-                            mBackupManagerMonitorEventSender.putMonitoringExtra(
-                                    monitoringExtras,
-                                    BackupManagerMonitor.EXTRA_LOG_RESTORE_ANYWAY,
-                                    true);
-                    monitoringExtras = addRestoreOperationTypeToEvent(monitoringExtras);
-                    mBackupManagerMonitorEventSender.monitorEvent(
-                            BackupManagerMonitor.LOG_EVENT_ID_RESTORE_VERSION_HIGHER,
-                            mCurrentPackage,
-                            BackupManagerMonitor.LOG_EVENT_CATEGORY_BACKUP_MANAGER_POLICY,
-                            monitoringExtras);
+                } else {
+                    if ((mCurrentPackage.applicationInfo.flags
+                            & ApplicationInfo.FLAG_RESTORE_ANY_VERSION)
+                            == 0) {
+                        // Downgrade scenario with RestoreAnyVersion flag off
+                        logDowngradeScenario(/* isRestoreAnyVersion */ false, metaInfo);
+                        nextState = UnifiedRestoreState.RUNNING_QUEUE;
+                        return;
+                    } else {
+                        logDowngradeScenario(/* isRestoreAnyVersion */ true, metaInfo);
+                    }
                 }
             }
 
@@ -1673,4 +1666,86 @@
         return mBackupManagerMonitorEventSender.putMonitoringExtra(
                 extras, BackupManagerMonitor.EXTRA_LOG_OPERATION_TYPE, RESTORE);
     }
+
+    // checks the sdk of the target/source device for a B&R operation.
+    // system components can opt in/out of V->U restore via allowlists. All other apps are
+    // not impacted
+    @SuppressWarnings("AndroidFrameworkCompatChange")
+    @VisibleForTesting
+    protected boolean isVToUDowngrade(int sourceSdk, int targetSdk) {
+        // We assume that if the source sdk is greater than U then the source is V.
+        return Flags.enableVToURestoreForSystemComponentsInAllowlist()
+                && (sourceSdk > Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
+                && (targetSdk == Build.VERSION_CODES.UPSIDE_DOWN_CAKE);
+    }
+
+    @VisibleForTesting
+    protected List<String> createVToUList(@Nullable String listString) {
+        // The allowlist/denylist is stored as a comma-separated list of package names
+        List<String> list = new ArrayList<>();
+        if (listString != null) {
+            list = Arrays.asList(listString.split(","));
+        }
+        return list;
+    }
+
+    @VisibleForTesting
+    protected boolean isPackageEligibleForVToURestore(PackageInfo mCurrentPackage) {
+        // A package is eligible for V to U downgrade restore if either:
+        //    - The package has restoreAnyVersion set to false and is part of the V to U allowlist
+        //      (and not in the denylist)
+        //    - The package has restoreAnyVersion set to true and is not part of the denylist
+        if (mVToUDenylist.contains(mCurrentPackage.packageName)){
+            return false;
+        } else if ((mCurrentPackage.applicationInfo.flags
+                & ApplicationInfo.FLAG_RESTORE_ANY_VERSION)
+                == 0) {
+            // package has restoreAnyVersion set to false
+            return mVToUAllowlist.contains(mCurrentPackage.packageName);
+        } else {
+            // package has restoreAnyVersion set to true and is nor in denylist
+            return true;
+        }
+    }
+
+    private void logDowngradeScenario(boolean isRestoreAnyVersion, Metadata metaInfo) {
+        Bundle monitoringExtras =
+                mBackupManagerMonitorEventSender.putMonitoringExtra(
+                        null,
+                        BackupManagerMonitor.EXTRA_LOG_RESTORE_VERSION,
+                        metaInfo.versionCode);
+        String message;
+        if (isRestoreAnyVersion) {
+            monitoringExtras =
+                    mBackupManagerMonitorEventSender.putMonitoringExtra(
+                            monitoringExtras,
+                            BackupManagerMonitor.EXTRA_LOG_RESTORE_ANYWAY,
+                            true);
+            message = "Source version "
+                    + metaInfo.versionCode
+                    + " > installed version "
+                    + mCurrentPackage.getLongVersionCode()
+                    + " but restoreAnyVersion";
+        } else {
+            monitoringExtras =
+                    mBackupManagerMonitorEventSender.putMonitoringExtra(
+                            monitoringExtras,
+                            BackupManagerMonitor.EXTRA_LOG_RESTORE_ANYWAY,
+                            false);
+            message = "Source version "
+                    + metaInfo.versionCode
+                    + " > installed version "
+                    + mCurrentPackage.getLongVersionCode();
+            EventLog.writeEvent(EventLogTags.RESTORE_AGENT_FAILURE, mCurrentPackage.packageName,
+                    message);
+        }
+        Slog.i(TAG, "Package " + mCurrentPackage.packageName + ": " + message);
+        monitoringExtras = addRestoreOperationTypeToEvent(monitoringExtras);
+        mBackupManagerMonitorEventSender.monitorEvent(
+                BackupManagerMonitor.LOG_EVENT_ID_RESTORE_VERSION_HIGHER,
+                mCurrentPackage,
+                BackupManagerMonitor.LOG_EVENT_CATEGORY_BACKUP_MANAGER_POLICY,
+                monitoringExtras);
+    }
+
 }
diff --git a/services/tests/mockingservicestests/src/com/android/server/backup/restore/PerformUnifiedRestoreTaskTest.java b/services/tests/mockingservicestests/src/com/android/server/backup/restore/PerformUnifiedRestoreTaskTest.java
index 940469f..414532b 100644
--- a/services/tests/mockingservicestests/src/com/android/server/backup/restore/PerformUnifiedRestoreTaskTest.java
+++ b/services/tests/mockingservicestests/src/com/android/server/backup/restore/PerformUnifiedRestoreTaskTest.java
@@ -29,16 +29,20 @@
 import android.app.backup.BackupDataOutput;
 import android.app.backup.BackupTransport;
 import android.content.Context;
+import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageInfo;
+import android.os.Build;
 import android.os.Message;
 import android.os.RemoteException;
 import android.platform.test.annotations.Presubmit;
+import android.platform.test.flag.junit.SetFlagsRule;
 import android.provider.DeviceConfig;
 
 import androidx.test.InstrumentationRegistry;
 import androidx.test.runner.AndroidJUnit4;
 
 import com.android.modules.utils.testing.TestableDeviceConfig;
+import com.android.server.backup.Flags;
 import com.android.server.backup.UserBackupManagerService;
 import com.android.server.backup.internal.BackupHandler;
 import com.android.server.backup.transport.BackupTransportClient;
@@ -56,10 +60,12 @@
 import org.mockito.stubbing.Answer;
 
 import java.util.ArrayDeque;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Queue;
 import java.util.Set;
@@ -74,10 +80,17 @@
     private static final String SYSTEM_PACKAGE_NAME = "android";
     private static final String NON_SYSTEM_PACKAGE_NAME = "package";
 
-    @Mock private BackupDataInput mBackupDataInput;
-    @Mock private BackupDataOutput mBackupDataOutput;
-    @Mock private UserBackupManagerService mBackupManagerService;
-    @Mock private TransportConnection mTransportConnection;
+    private static final String V_TO_U_ALLOWLIST = "pkg1";
+    private static final String V_TO_U_DENYLIST = "pkg2";
+
+    @Mock
+    private BackupDataInput mBackupDataInput;
+    @Mock
+    private BackupDataOutput mBackupDataOutput;
+    @Mock
+    private UserBackupManagerService mBackupManagerService;
+    @Mock
+    private TransportConnection mTransportConnection;
 
     private Set<String> mExcludedkeys = new HashSet<>();
     private Map<String, String> mBackupData = new HashMap<>();
@@ -91,6 +104,10 @@
     public TestableDeviceConfig.TestableDeviceConfigRule mDeviceConfigRule =
             new TestableDeviceConfig.TestableDeviceConfigRule();
 
+    @Rule
+    public final SetFlagsRule mSetFlagsRule = new SetFlagsRule();
+
+
     private Context mContext;
 
     @Before
@@ -118,7 +135,8 @@
                                     return null;
                                 });
 
-        mRestoreTask = new PerformUnifiedRestoreTask(mBackupManagerService, mTransportConnection);
+        mRestoreTask = new PerformUnifiedRestoreTask(mBackupManagerService, mTransportConnection,
+                V_TO_U_ALLOWLIST, V_TO_U_DENYLIST);
     }
 
     private void populateTestData() {
@@ -235,6 +253,122 @@
                         == UnifiedRestoreState.FINAL);
     }
 
+    @Test
+    public void testCreateVToUList_listSettingIsNull_returnEmptyList() {
+        List<String> expectedEmptyList = new ArrayList<>();
+
+        List<String> list = mRestoreTask.createVToUList(null);
+
+        assertEquals(list, expectedEmptyList);
+    }
+
+    @Test
+    public void testCreateVToUList_listIsNotNull_returnCorrectList() {
+        List<String> expectedList = Arrays.asList("a", "b", "c");
+        String listString = "a,b,c";
+
+        List<String> list = mRestoreTask.createVToUList(listString);
+
+        assertEquals(list, expectedList);
+    }
+
+    @Test
+    public void testIsVToUDowngrade_vToUFlagIsOffAndTargetIsUSourceIsV_returnFalse() {
+        mSetFlagsRule.disableFlags(
+                Flags.FLAG_ENABLE_V_TO_U_RESTORE_FOR_SYSTEM_COMPONENTS_IN_ALLOWLIST);
+
+        boolean isVToUDowngrade = mRestoreTask.isVToUDowngrade(
+                Build.VERSION_CODES.VANILLA_ICE_CREAM, Build.VERSION_CODES.UPSIDE_DOWN_CAKE);
+
+        assertFalse(isVToUDowngrade);
+    }
+
+    @Test
+    public void testIsVToUDowngrade_vToUFlagIsOnAndTargetIsUSourceIsV_returnTrue() {
+        mSetFlagsRule.enableFlags(
+                Flags.FLAG_ENABLE_V_TO_U_RESTORE_FOR_SYSTEM_COMPONENTS_IN_ALLOWLIST);
+
+        boolean isVToUDowngrade = mRestoreTask.isVToUDowngrade(
+                Build.VERSION_CODES.VANILLA_ICE_CREAM, Build.VERSION_CODES.UPSIDE_DOWN_CAKE);
+
+        assertTrue(isVToUDowngrade);
+    }
+
+    @Test
+    public void testIsVToUDowngrade_vToUFlagIsOnAndSourceIsNotV_returnFalse() {
+        mSetFlagsRule.enableFlags(
+                Flags.FLAG_ENABLE_V_TO_U_RESTORE_FOR_SYSTEM_COMPONENTS_IN_ALLOWLIST);
+
+        boolean isVToUDowngrade = mRestoreTask.isVToUDowngrade(Build.VERSION_CODES.UPSIDE_DOWN_CAKE,
+                Build.VERSION_CODES.UPSIDE_DOWN_CAKE);
+
+        assertFalse(isVToUDowngrade);
+    }
+
+    @Test
+    public void testIsVToUDowngrade_vToUFlagIsOnAndTargetIsNotU_returnFalse() {
+        mSetFlagsRule.enableFlags(
+                Flags.FLAG_ENABLE_V_TO_U_RESTORE_FOR_SYSTEM_COMPONENTS_IN_ALLOWLIST);
+
+        boolean isVToUDowngrade = mRestoreTask.isVToUDowngrade(
+                Build.VERSION_CODES.VANILLA_ICE_CREAM, Build.VERSION_CODES.VANILLA_ICE_CREAM);
+
+        assertFalse(isVToUDowngrade);
+    }
+
+
+    @Test
+    public void testIsEligibleForVToUDowngrade_pkgIsNotOnAllowlist_returnFalse() {
+        PackageInfo testPackageInfo = new PackageInfo();
+        testPackageInfo.packageName = "pkg";
+        testPackageInfo.applicationInfo = new ApplicationInfo();
+        // restoreAnyVersion flag is off
+        testPackageInfo.applicationInfo.flags = 0;
+
+        boolean eligibilityCriteria = mRestoreTask.isPackageEligibleForVToURestore(testPackageInfo);
+
+        assertFalse(eligibilityCriteria);
+    }
+
+    @Test
+    public void testIsEligibleForVToUDowngrade_pkgIsOnAllowlist_returnTrue() {
+        PackageInfo testPackageInfo = new PackageInfo();
+        testPackageInfo.packageName = "pkg1";
+        testPackageInfo.applicationInfo = new ApplicationInfo();
+        // restoreAnyVersion flag is off
+        testPackageInfo.applicationInfo.flags = 0;
+
+        boolean eligibilityCriteria = mRestoreTask.isPackageEligibleForVToURestore(testPackageInfo);
+
+        assertTrue(eligibilityCriteria);
+    }
+
+    @Test
+    public void testIsEligibleForVToUDowngrade_pkgIsNotOnDenyList_returnTrue() {
+        PackageInfo testPackageInfo = new PackageInfo();
+        testPackageInfo.packageName = "pkg";
+        testPackageInfo.applicationInfo = new ApplicationInfo();
+        // restoreAnyVersion flag is on
+        testPackageInfo.applicationInfo.flags = ApplicationInfo.FLAG_RESTORE_ANY_VERSION;
+
+        boolean eligibilityCriteria = mRestoreTask.isPackageEligibleForVToURestore(testPackageInfo);
+
+        assertTrue(eligibilityCriteria);
+    }
+
+    @Test
+    public void testIsEligibleForVToUDowngrade_pkgIsOnDenyList_returnFalse() {
+        PackageInfo testPackageInfo = new PackageInfo();
+        testPackageInfo.packageName = "pkg2";
+        testPackageInfo.applicationInfo = new ApplicationInfo();
+        // restoreAnyVersion flag is on
+        testPackageInfo.applicationInfo.flags = ApplicationInfo.FLAG_RESTORE_ANY_VERSION;
+
+        boolean eligibilityCriteria = mRestoreTask.isPackageEligibleForVToURestore(testPackageInfo);
+
+        assertFalse(eligibilityCriteria);
+    }
+
     private void setupForRestoreKeyValueState(int transportStatus)
             throws RemoteException, TransportNotAvailableException {
         // Mock BackupHandler to do nothing when executeNextState() is called