boolean verifyInstallerId(Context context) {    // A list with valid installers package name    List<String> validInstallers = new ArrayList<>(Arrays.asList("com.android.vending", "com.google.android.feedback"));    // The package name of the app that has installed your app    final String installer = context.getPackageManager().getInstallerPackageName(context.getPackageName());    // true if your app has been downloaded from Play Store     return installer != null && validInstallers.contains(installer);}