code: protected RelationKey parseRelationKey(String id) {
  
          Matcher matcher = RELATION_PATTERN.matcher(id);
          matcher.find();
          CmsUUID src = new CmsUUID(matcher.group(1));
          CmsUUID tgt = new CmsUUID(matcher.group(2));
          String tp = matcher.group(3);
          return new RelationKey(src, tgt, tp);
      }
docs: Extracts the source/target ids and the type from a relation id.<p>
  
  @param id the relation id
  
  @return the relation key object