This pack gives trial mobs and skeleton horsemen bossbars, one per spawner and trap respectively. It can hold a maximum of 30 trial and 30 skeleton trap bossbars at a time. Any naturally generating trial spawners function perfectly, and so do any trial spawners that were customised using spawn eggs.*

The pack should work immediately upon applying. If trial mobs were already present before enabling the datapack, it is possible the bossbar doesn't appear yet, which just means they were too far away from the spawner to locate it. However, the next time that spawner spawns a mob, it should be marked and bossbars should then start functioning correctly.

As far as permanent changes to your world go, this datapack should only affect the following entities (no blocks or items):
 - All loaded persistent mobs will be checked to see if there are spawners near them, and once they have been checked they will be given the tag "checked.for.spawner" to prevent unnecessary double checking. These tags have no effect on the entity outside of telling the pack not to check them anymore.
 - All skeleton horsemen have a "marked.horseman" and "checked.for.trap" tag. These tags also don't affect the entity, they just help the datapack keep track of them.
 - Any bossbars that were present while the pack was disabled will continue to persist unless you finish the fight with the pack enabled or manually delete it with commands.**
 - To be able to read the data of the trial spawners and skeleton horsemen, invisible markers are placed in their locations. These are used to store the positions of the spawners and to position the bossbars, and will be removed automatically if their spawner or skeleton trap gets destroyed. However, they will remain present after removing the datapack until you manually delete them.***

This is my first datapack so if you have any ideas for efficiency, bugs to report, or other suggestions, any feedback is greatly appreciated!

Ideas I'm considering:
 - Giving zombie sieges a bossbar. I am actively working on this but it is complicated due to zombie siege zombies being indistinguishable from regular zombies.
 - The ability to toggle whether bossbars show for trial spawners and skeleton traps.
Let me know if you agree with these!

*It is worth noting that when using a datapack that customises trial spawners, the bossbars will likely not display accurate values, as I have not yet found a way to read the configuration files. If you have any ideas for how to do this, please let me know.

**Removing skeleton trap bossbars:
/bossbar remove minecraft:trap1
/bossbar remove minecraft:trap2
etc.

Removing trial chamber bossbars:
/bossbar remove minecraft:trial1
/bossbar remove minecraft:trial2
etc.

***Removing markers
/kill @e[type=marker,tag=trial.spawner]
/kill @e[type=marker,tag=skeleton.trap]
