message: tweak MapWithDirtyFlag name in CallbackValuesMap
diff: @@ -37,7 +37,7 @@ class CallbackValuesMap {
  // This guarantees that when dirty bit is read and reset, there is no change
  // to counters map
  template <typename Mapped>
  - struct MapWithDirtyflag {
  + struct MapWithDirtyFlag {
  folly::StringKeyedMap<Mapped> map;
  mutable bool dirtyKeys{false};
  };
  @@ -102,7 +102,7 @@ class CallbackValuesMap {
  private:
  mutable folly::SharedMutex mutex_;
  - using CallbackMap = MapWithDirtyflag<std::shared_ptr<CallbackEntry>>;
  + using CallbackMap = MapWithDirtyFlag<std::shared_ptr<CallbackEntry>>;
  CallbackMap callbackMap_;
  };
  