@silverwizard A teapot is mechanically a vessel that implements a catch-all "add liquid" or "pour liquid" more-or-less transparently to the actual identity of the liquid (barring extreme properties). When trying to put coffee in a teapot the method is implemented and the data would be valid, except that the teapot czar intervenes with an externally imposed rule which adjudicates that the data is actually invalid because reasons. 403 Forbidden.