public synchronized void disableRewinding() {
    this.canRewind = false;
  }
Disables the rewinding feature.  After calling this method the
attempts to rewind this channel will fail, and the subsequent
read()-calls will be forwarded directly to the wrapped
channel (after the currently buffered bytes are read).
java_src/src/main/java/com/google/crypto/tink/subtle/RewindableReadableByteChannel.java