code: private Entity lookupEntity(String sid) {
          for (Integer i = 0; i < getEntities().size(); i++) {
              Entity e = getEntities().get(i);
              if (e != null && sid.compareTo(EntityContainer.buildId(e.getId())) == 0) {
                  return getEntity(e.getId());
              }
          }
          return null;
      }
docs: Looks for an Entity with the given id