What are you trying to do?

I'd like holograms made via API to save/persist with the world like ones created via the plugin.

What have you tried so far?

Look over the docs, API docs, etc for any reference to persistance.

Platform

• Server version (output of /version): 1.15.2
• Holographic Displays version (check with /hd): 2.4.1
• ProtocolLib version, if installed (check with /protocol version):
• Do you use plugins to allow players to join with multiple Minecraft versions (such as ViaVersion, ProtocolSupport, ...): No

Additional context

You currently need to save them to disk by yourself. API-created holograms are separate from command-created holograms, and they are not mean to be persistent by default. You can take a look at how Holographic Displays stores holograms here: https://github.com/filoghost/HolographicDisplays/tree/master/Plugin/src/main/java/com/gmail/filoghost/holographicdisplays/disk