grid refresh with nested containers

hi, need help.

BeanItemContainer containerContracts;
GeneratedPropertyContainer containerMain;
       
containerContracts = new BeanItemContainer<>(Contract.class);
containerMain = new GeneratedPropertyContainer(containerContracts);

Grid grid = new Grid(containerMain);

...
// refresh
containerContracts.removeAllItems();
containerContracts.addAll(jpaController.findAll());
// not working

whats wrong?

Not enough information has been provided for anyone here to troubleshoot this issue further.

What are you expecting to happen, vs what is actually happening?

What do you mean by it's "not working"?

What does this line return?

jpaController.findAll()