code: @Nullable
      public static String getPackageInstaller(@NonNull final Context context) {
          final PackageManager packageManager = context.getPackageManager();
          return packageManager.getInstallerPackageName(context.getPackageName());
      }
docs: Returns the package name of the application installer.
  
  @param context The instance of {@link android.content.Context}.
  @return The package name of the application installer.