JProtection is a plugins that allows you to literally lock everything, blazes, furnaces, ender crystals, dragons, you name it. Apart from just preventing you from breaking or damaging a entity or block, it does also prevents you from interacting with the block or entity (This is optionally for the player who owns the lock), you can for example prevent other players from entering your mine cart, or prevent them from opening your chest, or even prevent them from trading with your villager. You can also optionally lock items that gets thrown on death.
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This plugin gives you the ability to lock all blocks. It does also makes it possible to prevent people from sneaking in your chests, messing with your beacon, and stealing stuff from you furnace.
This plugin does also gives you the ability to lock you entities. You optionally prevent people from interact with them, that might be good if you don't want people to trade with your villager, or don't want people to keep rotating you item frame. But allowing interactions might be good if you want to have cows that can't be killed but you still want people to be able to breed on them.
If you think its annoying that people steal your items when you die you have the ability to turn on the function that locks your items when you die. But it doesn't prevent despawn so you better pick them up quickly. Check the Config page for more info.
If you have Vault on your server, and doesn't want people to create locks to easily, you have the opportunity to set a price for the locks. The price is set individually per entity/block. Check the Config page for more info.