Merge "Remove unnecessary std::unary_function base classes"

        const TKey& getKey() const final { return key; }

    };

    struct HashForEntry : public std::unary_function<KeyedEntry*, hash_t> {

    struct HashForEntry {

        size_t operator() (const KeyedEntry* entry) const {

            return hash_type(entry->getKey());

        };

    };

    struct EqualityForHashedEntries : public std::unary_function<KeyedEntry*, hash_t> {

    struct EqualityForHashedEntries {

        bool operator() (const KeyedEntry* lhs, const KeyedEntry* rhs) const {

            return lhs->getKey() == rhs->getKey();

        };