Fix Chained Vocabulary widget dropdown display in multi-value complex schema

Steps to Reproduce:

1. Open JSF UI on a local instance with the attached Studio project .jar deployed
2. In a Folder, create a new Lead And Location document.
3. In the Create layout, click the "Add" button to create an entry in the multi-valued complex property
4. Click on the Location field at the bottom to select an entry among the parent level of the Vocabulary from the dropdown list.
5. Observe the result when attempting to select for the child level of the Vocabulary

Expected result: Chained Vocabulary widget dropdown should populate with the children of the selected parent-level Vocabulary entry.

Actual result: Chained Vocabulary widget dropdown fails to populate with any entries, only having the default "Select a value".