code: public List<URI> extractModelReferenceURIs(XAttributable target) {
  		List<String> refStrings = extractModelReferences(target);
  		List<URI> refURIs = new ArrayList<URI>(refStrings.size());
  		for (String refString : refStrings) {
  			refURIs.add(URI.create(refString));
  		}
  		return refURIs;
  	}
docs: Retrieves the list of model reference URIs which describe a log element
  (archive, log, trace, event, attribute).
  
  @param target
  Any log element (i.e., archive, log, trace, event, or
  attribute) to be queried.
  @return The list of model references, as a list of URIs, referred to by
  this element.