Interest CanBePrefix element
Libraries should provide getter and setter for Interest CanBePrefix element.
The global default is initially CanBePrefix=true to avoid breaking existing application.
Applications should either set CanBePrefix to true or false on each Interest, or declare its preference through a global API; if an application does neither, the library must log a warning indicating the default value of CanBePrefix is changing to false in the future.
See Packet03Transition for details.