public static boolean isAndroid() {
    // https://developer.android.com/reference/java/lang/System#getProperties%28%29
    return "The Android Project".equals(System.getProperty("java.vendor"));
  }
Best-effort checks that this is Android.

@return true if running on Android.
java_src/src/main/java/com/google/crypto/tink/subtle/SubtleUtil.java