public static PublicationXref addBioPaxAttributes(
			List<String> bioPaxRefId, String pubmedId) {
		
		// create publicationXref object
		PublicationXref xref = new PublicationXref();
		
		if (!(bioPaxRefId.isEmpty())) xref.setId(bioPaxRefId.get(0));
		else {xref.setId("");}
		if (!(pubmedId.equals(""))) xref.setPubmedId(pubmedId);
		else {System.out.println("No pubmedId for biopaxref!!"); throw new EmptyStackException();}
		
		return xref;
		
	}