private static void write(KeysetHandle handle, KeysetWriter writer, Aead masterAead)
      throws GeneralSecurityException {
    try {
      if (masterAead != null) {
        handle.write(writer, masterAead);
      } else {
        CleartextKeysetHandle.write(handle, writer);
      }
    } catch (IOException e) {
      throw new GeneralSecurityException(e);
    }
  }
Returns whether Android Keystore is being used to wrap Tink keysets.
java_src/src/main/java/com/google/crypto/tink/integration/android/AndroidKeysetManager.java