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

<p>Note: this is more tricky than it seems. For example, using reflection to see if
android.os.Build.SDK_INT exists might fail because proguard might break the
reflection part. Using build dispatching can also fail if there are issues in the build graph
(see cl/510374081).

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