Add getConnection() method to IObject so we ask Object about its connection

include/sdbus-c++/IObject.h

@@ -173,6 +173,13 @@ namespace sdbus {
         */
         virtual void emitSignal(const sdbus::Signal& message) = 0;
 
+        /*!
+        * @brief Provides D-Bus connection used by the object
+        *
+        * @return Reference to the D-Bus connection
+        */
+        virtual sdbus::IConnection& getConnection() const = 0;
+
         /*!
         * @brief Registers method that the object will provide on D-Bus
         *

include/sdbus-c++/Interfaces.h

@@ -74,7 +74,7 @@ namespace sdbus {
      ***********************************************/
     template <typename... _Interfaces>
     class Interfaces
-        : private ObjectHolder<IObject>
+        : protected ObjectHolder<IObject>
         , public _Interfaces...
     {
     public:
@@ -96,7 +96,7 @@ namespace sdbus {
      ***********************************************/
     template <typename... _Interfaces>
     class ProxyInterfaces
-        : private ObjectHolder<IObjectProxy>
+        : protected ObjectHolder<IObjectProxy>
         , public _Interfaces...
     {
     public: