This farm is close (not exact) to the shulker farm that xisumavoid's patrons crafted on his patron server that is showcased near the end of this video on xisumavoid's youtube channel
WARNING! It is not possible to for a player to build this on a survival server unless a shulker egg is made available to the player and it is used on a mob spawner.
As explained in the video, this farm can be used as a solution to the scarcity of shulker shells after all the end cities are cleaned out as an alternative to adjusting loot tables, expanding, and / or reseting the end.
The ideal spot for this would be out in the void in the end. although could be built almost anywhere.
For best results, use a Sharpness V, Sweeping Edge III, Looting III sword to hit Multiple Shulkers for the quickest kills and increased loot (shulker shells) chance.