Collector can't handle required fields, i.e. Nulls Not Allowed?

[847396730]

When I publish a 10.3 service from ArcGIS Server and subsequently edit the service in the Collector app, the "Done" button will not be tapped if the field is required.  But if I change the field in Catalog to allow Null values, the "Done" button in the collector app will work.

Is this a known limitation, is there a workaround, or is it a bug?

Thanks!

[PaulLohr]

I think Paul's mention of Update Layer Definition is explained in this document:

https://blogs.esri.com/esri/arcgis/files/2014/10/How-to-Update-Hosted-Feature-Service-Schemas1.pdf 

Pretty sure this can be done on hosted feature services or local ArcGIS Server instances.