List field with `default=[]`

[szakitibi]

plone.app.contenttypes/plone/app/contenttypes/browser/migration.py

Line 47 in 4e0aa66

default=[],

If I remember correctly using default=[] is a big NO-NO according to Plone docs.

[ale-rt]

Yep, it should be defalutFactory=list or default=None or something like that.
It would be great if you could make a PR ;)

[szakitibi]

Well tested what happens if I simply remove it, since it was only introduced with this commit 14e23a69. The form handle errors the same way. Tested both empty and changed base class case - see PR #668.