Fix validation error on a non-required multi-valued complex field

Pre-requisites:
Deploy the jar whose download link is provided in the first comment

Steps to reproduce:

1. navigate to a Workspace or Folder
2. click on the + button and choose Repeat document type
3. fill the Actor Name field
4. submit the form with the Create button
5. observe that nothing happens whereas all the required fields are filled

Now, if you click on the ADD button and add an entry to the multi-valued complex field, you will be able to submit the form and create the document.

Expected behavior:
An empty non-required multi-valued complex field should not prevent from creating (and editing) a document.

The bug is fixed with FT 10.2, possibly fixed by ELEMENTS-633