const correctness

source/RobotAPI/libraries/armem_robot/client/interfaces.h

@@ -12,10 +12,10 @@ namespace armarx::armem::robot
     public:
         virtual ~ReaderInterface() = default;
 
-        virtual bool synchronize(Robot& obj, const armem::Time& timestamp) = 0;
+        virtual bool synchronize(Robot& obj, const armem::Time& timestamp) const = 0;
 
-        virtual Robot get(const RobotDescription& description, const armem::Time& timestamp) = 0;
-        virtual std::optional<Robot> get(const std::string& name, const armem::Time& timestamp) = 0;
+        virtual Robot get(const RobotDescription& description, const armem::Time& timestamp) const = 0;
+        virtual std::optional<Robot> get(const std::string& name, const armem::Time& timestamp) const = 0;
     };
 
     class WriterInterface