@Test
  public void getChaCha20Nonce_works() {
    byte[] nonce = Hex.decode("000102030405060708091011121314151617181920212223");
    byte[] expected = Hex.decode("000000001617181920212223");
    assertThat(XChaCha20Poly1305Jce.getChaCha20Nonce(nonce)).isEqualTo(expected);
  }
Test case taken from Wycheproof (testcase 5)
https://github.com/google/wycheproof/blob/b063b4aedae951c69df014cd25fa6d69ae9e8cb9/testvectors/xchacha20_poly1305_test.json#L69
java_src/src/test/java/com/google/crypto/tink/aead/internal/XChaCha20Poly1305JceTest.java