Review

class TeeSinkTokenFilter {
  public boolean incrementToken() throws IOException {
    if (input.incrementToken()) {
      // capture state lazily - maybe no SinkFilter accepts this state
      AttributeSource.State state = null;
      for (Iterator it = sinks.iterator(); it.hasNext(); ) {
        final SinkTokenStream sink = (SinkTokenStream) ((WeakReference) it.next()).get();
        if (sink != null) {
          if (sink.accept(this)) {
            if (state == null) {
              state = this.captureState();
            }
            sink.addState(state);
          }
        }
      }
      return true;
    }
    
    return false;
  }
}

class TeeSinkTokenFilter.SinkTokenStream {
    public final boolean incrementToken() throws IOException {
      // lazy init the iterator
      if (it == null) {
        it = cachedStates.iterator();
      }
    
      if (!it.hasNext()) {
        return false;
      }
      
      AttributeSource.State state = (State) it.next();
      restoreState(state);
      return true;
    }

}