HH-43544 parse text/plain
HH-43544 raise FailedFutureException on Placeholder.get() instead of returning it
Merge remote-tracking branch 'origin/HH-43544' into EXP-11368
release 2.19.16 [an.sumin@hh.ru]
HH-43583 add handler_404 parameter to FileMappingDispatcher
HH-43583 add an example and update docs