@GuardedBy("this")
  private void disableRewinding() throws IOException {
    ciphertextStream.mark(0);
  }
Disable rewinding.
This method is called once this class has found the correct key version.
TODO(bleichen): While BufferedInputStream stops buffering new bytes,
  it does not shrink the intenal buffer.
java_src/src/main/java/com/google/crypto/tink/streamingaead/InputStreamDecrypter.java