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

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

-{#--- Begin #}
-{%- import "encoding_macros.tmpl" as encoding_macros %}
-{%- macro struct_def(struct, typepkg, package) %}
-{#--- Enums #}
-{%- from "enum_definition.tmpl" import enum_def %}
-{%-  for enum in struct.enums %}
-{{enum_def(enum, typepkg, package)}}
-{%-  endfor %}
-
-class {{struct|name}} extends bindings.Struct {
-  static const List<bindings.StructDataHeader> kVersions = const [
-{%- for version in struct.versions %}
-    const bindings.StructDataHeader({{version.num_bytes}}, {{version.version}}){% if not loop.last %},{% endif %}
-{%- endfor %}
-  ];
-
-{#--- Constants #}
-{%-  for constant in struct.constants %}
-  static const {{constant.kind|dart_type}} {{constant|name}} = {{constant.resolved_value}};
-{%-  endfor %}
-
-{#--- initDefaults() #}
-{%- for packed_field in struct.packed.packed_fields %}
-  {{packed_field.field.kind|dart_type}} {{packed_field.field|name}} = {{packed_field.field|default_value}};
-{%- endfor %}
-
-  {{struct|name}}() : super(kVersions.last.size);
-
-  {{struct|name}}.init(
-{%- for packed_field in struct.packed.packed_fields %}
-    {{packed_field.field.kind|dart_type}} this.{{packed_field.field|name}}{% if not loop.last %}, {% endif %}
-{%- endfor %}
-  ) : super(kVersions.last.size);
-
-  static {{struct|name}} deserialize(bindings.Message message) =>
-      bindings.Struct.deserialize(decode, message);
-
-  static {{struct|name}} decode(bindings.Decoder decoder0) {
-    if (decoder0 == null) {
-      return null;
-    }
-    {{struct|name}} result = new {{struct|name}}();
-
-{%- if struct.bytes %}
-    var mainDataHeader = bindings.Struct.checkVersion(decoder0, kVersions);
-{%- else %}
-    bindings.Struct.checkVersion(decoder0, kVersions);
-{%- endif %}
-{%- for byte in struct.bytes %}
-{%-   for packed_field in byte.packed_fields %}
-    if (mainDataHeader.version >= {{packed_field.min_version}}) {
-      {{encoding_macros.decode('result.' ~ packed_field.field|name, packed_field.field.kind, 8+packed_field.offset, packed_field.bit)|indent(6)}}
-    }
-{%-   endfor %}
-{%- endfor %}
-    return result;
-  }
-
-  void encode(bindings.Encoder encoder) {
-{%- if not struct.bytes %}
-    encoder.getStructEncoderAtOffset(kVersions.last);
-{%- else %}
-    var encoder0 = encoder.getStructEncoderAtOffset(kVersions.last);
-{%- endif %}
-    const String structName = "{{struct|name}}";
-    String fieldName;
-    try {
-{%- for byte in struct.bytes %}
-{%-   for packed_field in byte.packed_fields %}
-      fieldName = "{{packed_field.field|name}}";
-      {{encoding_macros.encode(packed_field.field|name, packed_field.field.kind, 8+packed_field.offset, packed_field.bit)|indent(6)}}
-{%-   endfor %}
-{%- endfor %}
-    } on bindings.MojoCodecError catch(e) {
-      bindings.Struct.fixErrorMessage(e, fieldName, structName);
-      rethrow;
-    }
-  }
-
-  String toString() {
-    return "{{struct|name}}("
-{%- for packed_field in struct.packed.packed_fields %}
-           "{{packed_field.field|name}}: ${{packed_field.field|name}}" {% if not loop.last %}", "{% endif %}
-{%- endfor %}")";
-  }
-
-  Map toJson() {
-    {%- if struct|is_cloneable_kind %}
-    Map map = new Map();
-    {%- for packed_field in struct.packed.packed_fields %}
-    map["{{packed_field.field|name}}"] = {{packed_field.field|name}};
-    {%- endfor %}
-    return map;
-    {%- else %}
-    throw new bindings.MojoCodecError(
-        'Object containing handles cannot be encoded to JSON.');
-    {%- endif %}
-  }
-}
-
-{%- endmacro %}