code: public EntityContainer getEntityContainer(String id) {
          EntityContainer ec = (EntityContainer) getPmsession().getContainer(id);
          if (ec == null) {
              ec = getPresentationManager().newEntityContainer(id);
              getPmsession().setContainer(id, ec);
          }
          return ec;
      }
docs: Retrieve the container with the given id from session. If not defined, a
  new one is created.
  
  @param id The entity id
  @return The container