`date` header is defined in the constructor.
`date` header is defined in the constructor.

Before it was defined when calling `_getContent` if not defined. So it
defined only once and, more importantly, like any other headers. This is
more consistent.

Grummfy/Central,Grummfy/Central,Metalaka/Central,vcgato29/Central,vcgato29/Central,Metalaka/Central