This branch/commit is only useful to those who purely use a clean Bukkit/Spigot/Paper API
and does not use NMS/OBC references.
This will let you start updating your plugin to the latest 1.13 builds of Bukkit Preview (4 as of now)
Note that this release is not final!!! API breakages may occur!
It is up to you if you find use out of this work.
Spigot has patched this issue inside MapIcon, meaning that we no longer need to maintain this patch; Spigots patch also fixes#668 in that it will verify the length of the array, as well as protect against a negative type value being fetched from the array. Only real change is that Spigots patch returns a MapIcon.Type.PLAYER, instead of the RED_MARKER as originally PR'd by Aikar.