code: public LinguisticProcessor addLinguisticProcessor(String layer, String name) {
  	LinguisticProcessor lp = new LinguisticProcessor(name, layer);
  	//lp.setBeginTimestamp(timestamp); // no default timestamp
  	List<LinguisticProcessor> layerLps = lps.get(layer);
  	if (layerLps == null) {
  	    layerLps = new ArrayList<LinguisticProcessor>();
  	    lps.put(layer, layerLps);
  	}
  	layerLps.add(lp);
  	return lp;
      }
docs: Adds a linguistic processor to the document header. The timestamp is added implicitly.