unnecessary_nullable_for_final_variable_declarations     
            
            Use a non-nullable type for a final variable initialized with a non-nullable value.
This rule is available as of Dart 2.10.0.
Rule sets: recommended, flutter
This rule has a quick fix available.
Details
Use a non-nullable type for a final variable initialized with a non-nullable value.
BAD:
final int? i = 1;
GOOD:
final int i = 1;
Usage
To enable the unnecessary_nullable_for_final_variable_declarations rule,
add unnecessary_nullable_for_final_variable_declarations under linter > rules in your
analysis_options.yaml
file:
linter:
  rules:
    - unnecessary_nullable_for_final_variable_declarations