code: public static List<CmsRelationType> getAll() {
  
          List<CmsRelationType> all = new ArrayList<CmsRelationType>(Arrays.asList(VALUE_ARRAY));
          all.addAll(OpenCms.getResourceManager().getRelationTypes());
          return Collections.unmodifiableList(all);
      }
docs: Returns all relation types.<p>
  
  @return a list of {@link CmsRelationType} objects