It is no longer required, as we can use `<H as Header>::header_name()`.
BREAKING CHANGE: Implementations of Header will need to adjust the
    header_name method. It no longer takes any arguments.
		
	
It is no longer required, as we can use `<H as Header>::header_name()`.
BREAKING CHANGE: Implementations of Header will need to adjust the
    header_name method. It no longer takes any arguments.