Make the fuchsia mojo/public repo the source of truth.

mojo/public/tools/bindings/generators/dart_templates/enum_definition.tmpl

-{%- macro enum_def(enum, typepkg, package) %}
-class {{enum|name}} extends bindings.MojoEnum {
-{%- for field in enum.fields %}
-  static const {{enum|name}} {{field|name}} = const {{enum|name}}._({{field.resolved_value}});
-{%- endfor %}
-
-  const {{enum|name}}._(int v) : super(v);
-
-  static const Map<String, {{enum|name}}> valuesMap = const {
-{%- for field in enum.fields %}
-    "{{field|name}}": {{field|name}},
-{%- endfor %}
-  };
-  static const List<{{enum|name}}> values = const [
-{%- for field in enum.fields %}
-    {{field|name}},
-{%- endfor %}
-  ];
-
-  static {{enum|name}} valueOf(String name) => valuesMap[name];
-
-  factory {{enum|name}}(int v) {
-    switch (v) {
-{%- for field in enum.fields %}
-      case {{field.resolved_value}}:
-        return {{enum|name}}.{{field|name}};
-{%- endfor %}
-      default:
-        return null;
-    }
-  }
-
-  static {{enum|name}} decode(bindings.Decoder decoder0, int offset) {
-    int v = decoder0.decodeUint32(offset);
-    {{enum|name}} result = new {{enum|name}}(v);
-    if (result == null) {
-      throw new bindings.MojoCodecError(
-          'Bad value $v for enum {{enum|name}}.');
-    }
-    return result;
-  }
-
-  String toString() {
-    switch(this) {
-{%- for field in enum.fields %}
-      case {{field|name}}:
-        return '{{enum|name}}.{{field|name}}';
-{%- endfor %}
-      default:
-        return null;
-    }
-  }
-
-  int toJson() => mojoEnumValue;
-}
-
-{%- endmacro %}