library_prefixes 
              
Use lowercase_with_underscores when specifying a library prefix.
Details
#DO use lowercase_with_underscores when specifying a library prefix.
BAD:
dart
import 'dart:math' as Math;
import 'dart:json' as JSON;
import 'package:js/js.dart' as JS;
import 'package:javascript_utils/javascript_utils.dart' as jsUtils;GOOD:
dart
import 'dart:math' as math;
import 'dart:json' as json;
import 'package:js/js.dart' as js;
import 'package:javascript_utils/javascript_utils.dart' as js_utils;
Enable
#To enable the library_prefixes rule,
add library_prefixes under linter > rules in your
analysis_options.yaml file:
analysis_options.yaml
yaml
linter:
  rules:
    - library_prefixesIf you're instead using the YAML map syntax to configure linter rules,
add library_prefixes: true under linter > rules:
analysis_options.yaml
yaml
linter:
  rules:
    library_prefixes: true