  @Test
  public void hkdfExpandTest() {

    BytesValue idNonce =
        Bytes32.fromHexString("68b02a985ecb99cc2d10cf188879d93ae7684c4f4707770017b078c6497c5a5d");
    Functions.HKDFKeys keys1 =
        Functions.hkdf_expand(
            nodeId1,
            nodeId2,
            testKey1,
            BytesValue.wrap(ECKeyPair.create(testKey2.extractArray()).getPublicKey().toByteArray()),
            idNonce);
    Functions.HKDFKeys keys2 =
        Functions.hkdf_expand(
            nodeId1,
            nodeId2,
            testKey2,
            BytesValue.wrap(ECKeyPair.create(testKey1.extractArray()).getPublicKey().toByteArray()),
            idNonce);
    assertEquals(keys1, keys2);
  }