unnecessary_to_list_in_spreads    
            
            Unnecessary toList() in spreads.
This rule is available as of Dart 2.18.0.
This rule has a quick fix available.
Details
Unnecessary toList() in spreads.
BAD:
children: <Widget>[
  ...['foo', 'bar', 'baz'].map((String s) => Text(s)).toList(),
]
GOOD:
children: <Widget>[
  ...['foo', 'bar', 'baz'].map((String s) => Text(s)),
]
Usage
To enable the unnecessary_to_list_in_spreads rule,
add unnecessary_to_list_in_spreads under linter > rules in your
analysis_options.yaml
file:
linter:
  rules:
    - unnecessary_to_list_in_spreads