correct way to use app_usbd?

[akohlsmith]

With SDK15 and the nRF52840, what is the correct way to include the USBD (specifically the CDC/ACM class) component?

I started by adding

SDK_HEADER_PATHS += $(SDK_ROOT)components/libraries/usbd/
SDK_HEADER_PATHS += $(wildcard $(SDK_ROOT)components/drivers_nrf/usbd/)

in the SDK's make/Includes.mk, but I know this is the way for much wailing and gnashing of teeth. Besides, it looks like I'm going to have to also include a whole bunch more (components/libraries/usbd/class/cdc, components/libraries/class/cdc/acm, etc.)...

Ideally this should be in the apps/my_app/Makefile, but I think you're trying to steer us into doing this in the Boards/board_name/Build.mk which feels weird (it's not a board-specific thing, it's an app-specific thing)...