When I first wrote this plugin back for an ancient version of Minecraft, paintings, item frames, and armor stands did not spawn naturally. They had to be placed by a player in order to exist in the world. My code assumed that these items belonged to some player, and if you weren't the owner, you were not allowed to interact with them. Yes, I know what happens when you ass-u-me things, lol. This new version still protects items placed in the world by players, but allows any player to interact with a naturally-occurring container entity, such as an item frame in an end city containing an elytra, or a painting in a mansion.

I was also asked to protect the block that the item was mounted to or standing on. I originally did not do this because the intent for this plugin was to prevent theft from these container-type items, not their movement or destruction -- IMO, that's the job of a grief protection or a plot claim plugin to protect the entity, itself, from griefing. But now this plugin will attempt to prevent a griefer from destroying the block that an armor stand, item frame, or painting is standing on or mounted to. This was especially tricky to do because these things are entities, not blocks. To the Minecraft game code internals, these things are peaceful mobs that don't move, rather than blocks that have an X-Y-Z position in the world.