message: Add getters for stream scatterer impl properties
diff: @@ -45,6 +45,16 @@ public:
  virtual ~stream_scatterer_impl();
  + // -- properties -------------------------------------------------------------
  +
  + inline const map_type& paths() const {
  + return paths_;
  + }
  +
  + inline map_type& paths() {
  + return paths_;
  + }
  +
  // -- path management --------------------------------------------------------
  size_t num_paths() const noexcept override;
  