The new JcrMultiFieldDefinition adds the nodes it creates directly to the parent node, named after the jcrMultiField with a number added, e.g. "product0", "product1" etc. This leads to such a structure:

As you can imagine, a structure like this does not all you to loop over the products. In the Freemarker templates you can cheat your way around this by getting all children and looping over them, filtering out all that do not match a name pattern. However in the SPA you don't have the component object available so you cannot loop over any properties.