DDSPSMC11_ — Default Constructors

Reference types do not have default constructors, forcing the use of nullptr to construct null references. This runs counter to modern C++ conventions; for example, consider C++11 smart pointers. Forcing explicit initialization also prevents the sensible use of compiler-generated default constructors for objects containing DDS objects as members.

To get the behavior I want, I've to define constructor and destructor for a struct for no purpose other than to initialize a member instance handle to null, or just make it a std::unique_ptr<dds::core::InstanceHandle> and circumvent the API.