add bunch of new java APIs: mostly stubs or copied from AOSP

Many of these classes are only needed to be subclassed by androidx
support library, which is used in many android apps

src/api-impl/android/content/Context.java

@@ -6,6 +6,7 @@ import android.app.Application;
 import android.app.KeyguardManager;
 import android.app.NotificationManager;
 import android.app.SharedPreferencesImpl;
+import android.app.UiModeManager;
 import android.content.BroadcastReceiver;
 import android.content.ClipboardManager;
 import android.content.Intent;
@@ -165,6 +166,8 @@ public class Context extends Object {
 				return new InputManager();
 			case "location":
 				return new LocationManager();
+			case "uimode":
+				return new UiModeManager();
 			default:
 				System.out.println("!!!!!!! getSystemService: case >" + name + "< is not implemented yet");
 				return null;
@@ -348,4 +351,8 @@ public class Context extends Object {
 	public void setTheme(int resId) {
 		theme.applyStyle(resId, true);
 	}
+
+	public final CharSequence getText(int resId) {
+		return getResources().getText(resId);
+	}
 }

src/api-impl/android/content/ContextWrapper.java

@@ -0,0 +1,14 @@
+package android.content;
+
+public class ContextWrapper extends Context {
+	private Context baseContext;
+
+	public ContextWrapper(Context baseContext) {
+		this.baseContext = baseContext;
+	}
+
+	public Context getBaseContext() {
+		return baseContext;
+	}
+	
+}

src/api-impl/android/content/Intent.java

@@ -185,6 +185,14 @@ public class Intent {
 		return component;
 	}
 
+	public boolean hasExtra(String name) {
+		return extras.containsKey(name);
+	}
+
+	public Serializable getSerializableExtra(String name) {
+		return (Serializable)extras.get(name);
+	}
+
 	@Override
 	public String toString() {
 		return "Intent [component=" + component + ", extras=" + extras + "]";

src/api-impl/android/content/pm/PackageManager.java

@@ -1337,6 +1337,34 @@ public class PackageManager {
 	 */
 	public static final String EXTRA_REQUEST_PERMISSION_PERMISSION_LIST = "android.content.pm.extra.PERMISSION_LIST";
 
+	// dummy certificate
+	public final static byte[] X509_DUMMY = (
+			"-----BEGIN CERTIFICATE-----\n" +
+			"MIIERjCCAy6gAwIBAgIJAIz+EYMBU6aQMA0GCSqGSIb3DQEBBQUAMIGiMQswCQYD\n" +
+			"VQQGEwJDQTELMAkGA1UECBMCQkMxEjAQBgNVBAcTCVZhbmNvdXZlcjEWMBQGA1UE\n" +
+			"ChMNd3d3LmN1Y2JjLmNvbTEUMBIGA1UECxQLY29tbW9uc19zc2wxHTAbBgNVBAMU\n" +
+			"FGRlbW9faW50ZXJtZWRpYXRlX2NhMSUwIwYJKoZIhvcNAQkBFhZqdWxpdXNkYXZp\n" +
+			"ZXNAZ21haWwuY29tMB4XDTA2MTIxMTE1MzE0MVoXDTI4MTEwNTE1MzE0MVowgaQx\n" +
+			"CzAJBgNVBAYTAlVTMREwDwYDVQQIEwhNYXJ5bGFuZDEUMBIGA1UEBxMLRm9yZXN0\n" +
+			"IEhpbGwxFzAVBgNVBAoTDmh0dHBjb21wb25lbnRzMRowGAYDVQQLExF0ZXN0IGNl\n" +
+			"cnRpZmljYXRlczEQMA4GA1UEAxMHZm9vLmNvbTElMCMGCSqGSIb3DQEJARYWanVs\n" +
+			"aXVzZGF2aWVzQGdtYWlsLmNvbTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoC\n" +
+			"ggEBAMhjr5aCPoyp0R1iroWAfnEyBMGYWoCidH96yGPFjYLowez5aYKY1IOKTY2B\n" +
+			"lYho4O84X244QrZTRl8kQbYtxnGh4gSCD+Z8gjZ/gMvLUlhqOb+WXPAUHMB39GRy\n" +
+			"zerA/ZtrlUqf+lKo0uWcocxeRc771KN8cPH3nHZ0rV0Hx4ZAZy6U4xxObe4rtSVY\n" +
+			"07hNKXAb2odnVqgzcYiDkLV8ilvEmoNWMWrp8UBqkTcpEhYhCYp3cTkgJwMSuqv8\n" +
+			"BqnGd87xQU3FVZI4tbtkB+KzjD9zz8QCDJAfDjZHR03KNQ5mxOgXwxwKw6lGMaiV\n" +
+			"JTxpTKqym93whYk93l3ocEe55c0CAwEAAaN7MHkwCQYDVR0TBAIwADAsBglghkgB\n" +
+			"hvhCAQ0EHxYdT3BlblNTTCBHZW5lcmF0ZWQgQ2VydGlmaWNhdGUwHQYDVR0OBBYE\n" +
+			"FJ8Ud78/OrbKOIJCSBYs2tDLXofYMB8GA1UdIwQYMBaAFHua2o+QmU5S0qzbswNS\n" +
+			"yoemDT4NMA0GCSqGSIb3DQEBBQUAA4IBAQC3jRmEya6sQCkmieULcvx8zz1euCk9\n" +
+			"fSez7BEtki8+dmfMXe3K7sH0lI8f4jJR0rbSCjpmCQLYmzC3NxBKeJOW0RcjNBpO\n" +
+			"c2JlGO9auXv2GDP4IYiXElLJ6VSqc8WvDikv0JmCCWm0Zga+bZbR/EWN5DeEtFdF\n" +
+			"815CLpJZNcYwiYwGy/CVQ7w2TnXlG+mraZOz+owr+cL6J/ZesbdEWfjoS1+cUEhE\n" +
+			"HwlNrAu8jlZ2UqSgskSWlhYdMTAP9CPHiUv9N7FcT58Itv/I4fKREINQYjDpvQcx\n" +
+			"SaTYb9dr5sB4WLNglk7zxDtM80H518VvihTcP7FHL+Gn6g4j5fkI98+S\n" +
+			"-----END CERTIFICATE-----\n").getBytes();
+
 	/**
 	 * Retrieve overall information about an application package that is
 	 * installed on the system.
@@ -1374,7 +1402,7 @@ public class PackageManager {
 	public PackageInfo getPackageInfo(String packageName, int flags) throws NameNotFoundException {
 		PackageInfo packageInfo = new PackageInfo();
 		if ((flags & GET_SIGNATURES) == GET_SIGNATURES) {
-			packageInfo.signatures = new Signature[0];
+			packageInfo.signatures = new Signature[]{new Signature(X509_DUMMY)};
 		}
 		return packageInfo;
 	}