Fix ClassCastException from toArray().

toArray() returns Object[], which can't be cast to Foo[]. Switch to
toArray(Foo[]) instead.

Fixed one instance which caused test breakage, and then all the others
I could find.

Also make sure PackageInstallerSessionTest runs in presubmit. It's a
cheap unit test, and tests are more useful when they run. (This is
what I was trying to do when I discovered the test was currently
failing.)

Fixes: 148858333
Bug: 137951074
Test: atest PackageInstallerSessionTest
Change-Id: Ie0142d46f1a34cf2072aaf81b3a5f8aa76d0c1f2

services/core/java/com/android/server/notification/ValidateNotificationPeople.java

@@ -38,6 +38,8 @@ import android.util.Log;
 import android.util.LruCache;
 import android.util.Slog;
 
+import libcore.util.EmptyArray;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedList;
@@ -301,7 +303,7 @@ public class ValidateNotificationPeople implements NotificationSignalExtractor {
         for (String person: second) {
             people.add(person);
         }
-        return (String[]) people.toArray();
+        return people.toArray(EmptyArray.STRING);
     }
 
     @Nullable

services/core/java/com/android/server/pm/PackageInstallerSession.java

@@ -129,6 +129,7 @@ import com.android.server.pm.dex.DexManager;
 import com.android.server.security.VerityUtils;
 
 import libcore.io.IoUtils;
+import libcore.util.EmptyArray;
 
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
@@ -212,7 +213,8 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
     private static final String ATTR_SIGNATURE = "signature";
 
     private static final String PROPERTY_NAME_INHERIT_NATIVE = "pi.inherit_native_on_dont_kill";
-    private static final int[] EMPTY_CHILD_SESSION_ARRAY = {};
+    private static final int[] EMPTY_CHILD_SESSION_ARRAY = EmptyArray.INT;
+    private static final FileInfo[] EMPTY_FILE_INFO_ARRAY = {};
 
     private static final String SYSTEM_DATA_LOADER_PACKAGE = "android";
 
@@ -375,8 +377,6 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
     // TODO(b/146080380): merge file list with Callback installation.
     private IncrementalFileStorages mIncrementalFileStorages;
 
-    private static final String[] EMPTY_STRING_ARRAY = new String[]{};
-
     private static final FileFilter sAddedApkFilter = new FileFilter() {
         @Override
         public boolean accept(File file) {
@@ -719,7 +719,7 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
         if (!isDataLoaderInstallation()) {
             String[] result = stageDir.list();
             if (result == null) {
-                result = EMPTY_STRING_ARRAY;
+                result = EmptyArray.STRING;
             }
             return result;
         }
@@ -3096,7 +3096,8 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
         }
 
         if (grantedRuntimePermissions.size() > 0) {
-            params.grantedRuntimePermissions = (String[]) grantedRuntimePermissions.toArray();
+            params.grantedRuntimePermissions =
+                    grantedRuntimePermissions.toArray(EmptyArray.STRING);
         }
 
         if (whitelistedRestrictedPermissions.size() > 0) {
@@ -3115,7 +3116,7 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub {
 
         FileInfo[] fileInfosArray = null;
         if (!files.isEmpty()) {
-            fileInfosArray = (FileInfo[]) files.toArray();
+            fileInfosArray = files.toArray(EMPTY_FILE_INFO_ARRAY);
         }
 
         InstallSource installSource = InstallSource.create(installInitiatingPackageName,

services/tests/servicestests/src/com/android/server/pm/PackageInstallerSessionTest.java

@@ -24,6 +24,7 @@ import static org.xmlpull.v1.XmlPullParser.END_DOCUMENT;
 import static org.xmlpull.v1.XmlPullParser.START_TAG;
 
 import android.content.pm.PackageInstaller;
+import android.platform.test.annotations.Presubmit;
 import android.util.AtomicFile;
 import android.util.Slog;
 import android.util.Xml;
@@ -57,6 +58,7 @@ import java.util.Arrays;
 import java.util.List;
 
 @RunWith(AndroidJUnit4.class)
+@Presubmit
 public class PackageInstallerSessionTest {
     @Rule
     public TemporaryFolder mTemporaryFolder = new TemporaryFolder();