Subject subj = src.getSubjectByIdentifier(identifier); if (null != subj) retval.add(subj);
Set subjs = src.search(identifier); if (null != subjs) retval.addAll(subjs);
	public Set getSubjectsByIdentifier(String identifier)	{		HashSet retval = new HashSet();		if ((null == identifier) || (0 >= identifier.length()))			return (retval);		for (Iterator srcs = signetSources.iterator(); srcs.hasNext(); )		{			SignetSource src = (SignetSource)srcs.next();			Subject subj = src.getSubjectByIdentifier(identifier);			if (null != subj)				retval.add(subj);		}		return (retval);	}