* The function has_content_length_impl is added to the
requirements of Fields.
Actions Required:
* Implement has_content_length_impl for user-defined Fields
fix#778
* The version data member is replaced with accessor
member functions.
Actions Required:
* Call member function message::version instead of accessing
the version member at call sites.
fix#778
* The body data member is replaced with accessor
member functions.
Actions Required:
* Call member function message::body instead of accessing
the data member at call sites.