camel_case_types

Name types using UpperCamelCase.

This rule is available as of Dart 2.0.0.

Rule sets: core, recommended, flutter

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