code: ReferenceableInstance createInstance(MemRepository repo, Id id) throws RepositoryException {
          Integer pos = idPosMap.get(id);
          String typeName = typeNameList.get(pos);
          if (!Objects.equals(typeName, hierarchicalType.getName())) {
              return repo.getClassStore(typeName).createInstance(repo, id);
          }
  
          ImmutableList<String> traitNames = traitNamesStore.get(pos);
          String[] tNs = traitNames.toArray(new String[]{});
  
          try {
              return (ReferenceableInstance) classType.createInstance(id, tNs);
          } catch (AtlasException me) {
              throw new RepositoryException(me);
          }
      }
docs: /*
  - assumes id is already validated