private static byte[] modifyInput(byte[] message) {
    if (message.length == 0) {
      return new byte[] {1};
    }
    byte[] copy = Arrays.copyOf(message, message.length);
    copy[0] ^= 1;
    return copy;
  }
Tests that when using the normal public API of Tink, newly created signatures can be verified.
java_src/src/test/java/com/google/crypto/tink/signature/EcdsaSignKeyManagerTest.java