In 1.20, signs have two sides that can be interacted with - written on, dyed, coloured, or made to glow. Now there's the side of the sign to consider.

In order to calculate this side from something like PlayerInteractEvent, you need to do some math based on player vector and block facing. Now that signs have even more interaction methods, this use case in the API strikes me as sensible, in order to avoid everyone having to write their own logic to calculate the side.

With both https://hub.spigotmc.org/jira/browse/SPIGOT-7396 and https://hub.spigotmc.org/jira/browse/SPIGOT-7412 it would seem that there are a number of gaps in the API for signs still outstanding, and each of these being reported in quick succession bolsters the argument for one another.

This may well want to be bundled into https://hub.spigotmc.org/jira/browse/SPIGOT-7396, depending on implementation.