migrate material to nullsafety (#67166)
* migrate material to nullsafety * address review comments * address review comments * fix build
A
Alexandre Ardhuin committed
f55117840818eae1b3972a6abe9d2784fc8fb9b4
Parent: aaa99f6
Committed by GitHub <noreply@github.com>
on 10/6/2020, 9:36:50 AM