camel_case_types

Name types using UpperCamelCase.

From Effective Dart:

DO name types using UpperCamelCase.

Classes and typedefs should capitalize the first letter of each word (including the first word), and use no separators.

GOOD:

class SliderMenu {
  // ...
}

class HttpRequest {
  // ...
}

typedef num Adder(num x, num y);

To enable the camel_case_types rule, add camel_case_types under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - camel_case_types

If you're instead using the YAML map syntax to configure linter rules, add camel_case_types: true under linter > rules:

linter:
  rules:
    camel_case_types: true