Update deprecated implicitly marking paramaters as nullable

sergio morais → made their first commit to this issue’s fork.

Awesome thank you! Better than what i had locally because i had not internalized the `?` shortcut yet (seemed FormStateInterface|null but the shorter form is nicer especially with that longer form already in the docblock code comment.

@sergio morais are you using this module? Would you want to co-maintain?

@mlncn I'm glad I could help. I'm using this module in a client's project. I can co-maintain. Thanks!

Automatically closed - issue fixed for 2 weeks with no activity.