code: public void convertToOWL(Model model, OutputStream outputStream, String... ids)
  	{
  		if (ids.length == 0)
  		{
  			convertToOWL(model, outputStream);
  		} else
  		{
  			Model m = model.getLevel().getDefaultFactory().createModel();
  			m.setXmlBase(model.getXmlBase());
  
  			Fetcher fetcher = new Fetcher(SimpleEditorMap.get(model.getLevel())); //no Filters anymore
  
  			for (String uri : ids)
  			{
  				BioPAXElement bpe = model.getByID(uri);
  				if (bpe != null)
  				{
  					fetcher.fetch(bpe, m);
  				}
  			}
  
  			convertToOWL(m, outputStream);
  		}
  	}
docs: Similar to {@link BioPAXIOHandler#convertToOWL(org.biopax.paxtools.model.Model,
  java.io.OutputStream)} (org.biopax.paxtools.model.Model, Object)}, but
  extracts a sub-model, converts it into BioPAX (OWL) format,
  and writes it into the outputStream.
  Saved data can be then read via {@link BioPAXIOHandler}
  interface (e.g., {@link SimpleIOHandler}).
  @param model model to be converted into OWL format
  @param outputStream output stream into which the output will be written
  @param ids optional list of "root" element absolute URIs;
  direct/indirect child objects are auto-exported as well.