Just some comments.

core/Expected.h

@@ -16,16 +16,18 @@ class Expected {
 
 public:
 
+    /** Constructor that receives a valid result value */
 	Expected(const T& rhs)
 		: m_value(rhs), m_valid(true)
 	{}
 
+	/** Move constructor for a valid result value */
 	Expected(T&& rhs)
 		: m_value(std::move(rhs))
 		, m_valid(true)
 	{}
 
-
+    /** Copy constructor */
 	Expected(const Expected& rhs)
 		: m_valid(rhs.m_valid)
 	{
@@ -37,6 +39,7 @@ public:
 		}
 	}
 
+	/** Move constructor */
 	Expected(Expected &&rhs)
 		: m_valid(rhs.m_valid)
 	{
@@ -48,6 +51,7 @@ public:
 		}
 	}
 
+	/** destructor */
 	~Expected()
 	{
 		if (m_valid) {