This is to solve "default selection" use case request:

• We will auto select first item if single selection, and field is required - Same as legacy
• We will auto select first item if multi selection, and field is required - Legacy does not have this, but feels most consistent.

Ref discussion in https://github.com/ezsystems/repository-forms/pull/84#issuecomment-223304428 and onwards.

NB: It's not yet clear how this should work with the PlatformUI custom select widget.
CC damien.pobel@ez.no bertrand.dunogier@ez.no andre.romcke@ez.no

Also implement BDD scenario:
The first item of the required select field is selected by default when editing