Update Unity simListassets, simSpawnObject APIs

Author: rajat2004

Unity/AirLibWrapper/AirsimWrapper/Source/WorldSimApi.cpp

@@ -373,4 +373,12 @@ std::vector<msr::airlib::DetectionInfo> WorldSimApi::getDetections(ImageCaptureB
     return std::vector<msr::airlib::DetectionInfo>();
 }
 
+std::vector<std::string> WorldSimApi::listAssets() const
+{
+    throw std::invalid_argument(common_utils::Utils::stringf(
+                                    "listAssets API is not supported on Unity")
+                                    .c_str());
+    return {};
+}
+
 #pragma endregion

Unity/AirLibWrapper/AirsimWrapper/Source/WorldSimApi.h

@@ -18,8 +18,9 @@ class WorldSimApi : public msr::airlib::WorldSimApiBase
 
     // ------ Level setting apis ----- //
     virtual bool loadLevel(const std::string& level_name) override { return false; };
-    virtual std::string spawnObject(std::string& object_name, const std::string& load_component, const Pose& pose, const Vector3r& scale, bool physics_enabled) override { return ""; };
+    virtual std::string spawnObject(const std::string& object_name, const std::string& load_component, const Pose& pose, const Vector3r& scale, bool physics_enabled) override { return ""; };
     virtual bool destroyObject(const std::string& object_name) override { return false; };
+    virtual std::vector<std::string> listAssets() const override;
 
     virtual bool isPaused() const override;
     virtual void reset() override;