Make PbMixin constructor public, bump version number to 0.5.2.

lib/mixins_meta.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Provides metadata about mixins to dart-protoc-plugin.
 /// (Experimental API; subject to change.)
 library protobuf.mixins.meta;
 
 /// Entry point called by dart-protoc-plugin.
 PbMixin findMixin(String name) {
   for (var m in _exportedMixins) {
     if (m.name == name) {
       return m;
     }
   }
   return null; // not found
 }
 
 /// PbMixin contains metadata needed by dart-protoc-plugin to apply a mixin.
 ///
 /// The mixin can be applied to a message using options in dart_options.proto.
 /// Only one mixin can be applied to each message, but that mixin can depend
 /// on another mixin, recursively, similar to single inheritance.
 class PbMixin {
-
   /// The name of the mixin class to import into the .pb.dart file.
   final String name;
 
   /// The file that the .pb.dart file should import the symbol from.
   final String importFrom;
 
   /// Another mixin to apply ahead of this one, or null for none.
   final PbMixin parent;
 
   /// Names that shouldn't be used by properties in the generated child class.
   /// May be null if the mixin doesn't reserve any new names.
   final List<String> reservedNames;
 
-  const PbMixin._raw(this.name,
-      {this.importFrom, this.parent, this.reservedNames});
+  const PbMixin(this.name, {this.importFrom, this.parent, this.reservedNames});
 
   /// Returns the mixin and its ancestors, in the order they should be applied.
   Iterable<PbMixin> findMixinsToApply() {
     var result = [this];
     for (var p = parent; p != null; p = p.parent) {
       result.add(p);
     }
     return result.reversed;
   }
 
   /// Returns all the reserved names, including from ancestor mixins.
   Iterable<String> findReservedNames() {
     var names = new Set<String>();
     for (var m = this; m != null; m = m.parent) {
       names.add(m.name);
       if (m.reservedNames != null) {
         names.addAll(m.reservedNames);
       }
     }
     return names;
   }
 }
 
 /// The mixins that findMixin() can return.
-const _exportedMixins = const [_pbMapMixin, _pbEventMixin];
+final _exportedMixins = [_pbMapMixin, _pbEventMixin];
 
-const _pbMapMixin = const PbMixin._raw("PbMapMixin",
+const _pbMapMixin = const PbMixin("PbMapMixin",
     importFrom: "package:protobuf/src/protobuf/mixins/map_mixin.dart",
     parent: _mapMixin);
 
-const _pbEventMixin = const PbMixin._raw("PbEventMixin",
+const _pbEventMixin = const PbMixin("PbEventMixin",
     importFrom: "package:protobuf/src/protobuf/mixins/event_mixin.dart",
     reservedNames: const ["changes", "deliverChanges"]);
 
 const List<String> _reservedNamesForMap = const [
   '[]',
   '[]=',
   'addAll',
   'containsKey',
   'containsValue',
   'forEach',
   'putIfAbsent',
   'remove',
   'isEmpty',
   'isNotEmpty',
   'keys',
   'length',
   'values',
 ];
 
-const _mapMixin = const PbMixin._raw("MapMixin",
-    importFrom: "dart:collection",
-    reservedNames: _reservedNamesForMap);
+const _mapMixin = const PbMixin("MapMixin",
+    importFrom: "dart:collection", reservedNames: _reservedNamesForMap);