Bug report: [short issue title]

[asdassafas]

Server details:

• Server version: paper1.12.2
• IRP Version: 1.7.9

Bug description:

Every time the plugin is launched, this error occurs. However, it does not affect the functionality. But it's really unsightly.

How to reproduce:

Start the plugin using "paper1.12.2"

Logs, screenshots & other:

[12:12:34 INFO]: [InventoryRollbackPlus] Inventory backup data is set to save to: YAML
[12:12:34 INFO]: [InventoryRollbackPlus] bStats are enabled
[12:12:34 ERROR]: [InventoryRollbackPlus] Test failed with exception: com.nuclyon.technicallycoded.inventoryrollback.util.test.SelfTest$$Lambda$2032/0x00000007c1163c28@31de2355
java.lang.NoSuchFieldError: SHULKER_BOX
at com.nuclyon.technicallycoded.inventoryrollback.util.test.SelfTestSerialization.lambda$buildTestSerializeAndDeserializeShulkerBoxWithItems$3(SelfTestSerialization.java:122) ~[?:?]
at com.nuclyon.technicallycoded.inventoryrollback.util.test.SelfTest.lambda$new$0(SelfTest.java:33) ~[?:?]
at com.nuclyon.technicallycoded.inventoryrollback.util.test.SelfTest.run(SelfTest.java:54) ~[?:?]
at com.nuclyon.technicallycoded.inventoryrollback.util.test.SelfTestSerialization.runTests(SelfTestSerialization.java:38) ~[?:?]
at com.nuclyon.technicallycoded.inventoryrollback.InventoryRollbackPlus.onEnable(InventoryRollbackPlus.java:104) ~[?:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:264) ~[patched_1.12.2.jar:git-Paper-1620]
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:316) ~[patched_1.12.2.jar:git-Paper-1620]
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:405) ~[patched_1.12.2.jar:git-Paper-1620]
at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugin(CraftServer.java:395) ~[patched_1.12.2.jar:git-Paper-1620]
at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugins(CraftServer.java:344) ~[patched_1.12.2.jar:git-Paper-1620]
at net.minecraft.server.v1_12_R1.MinecraftServer.t(MinecraftServer.java:442) ~[patched_1.12.2.jar:git-Paper-1620]
at net.minecraft.server.v1_12_R1.MinecraftServer.l(MinecraftServer.java:403) ~[patched_1.12.2.jar:git-Paper-1620]
at net.minecraft.server.v1_12_R1.MinecraftServer.a(MinecraftServer.java:341) ~[patched_1.12.2.jar:git-Paper-1620]
at net.minecraft.server.v1_12_R1.DedicatedServer.init(DedicatedServer.java:289) ~[patched_1.12.2.jar:git-Paper-1620]
at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:616) ~[patched_1.12.2.jar:git-Paper-1620]
at java.lang.Thread.run(Thread.java:750) [?:1.8.0_421]
[12:12:34 ERROR]: [InventoryRollbackPlus] Logs:
[12:12:34 INFO]: [InventoryRollbackPlus] Tests completed: 5, Skipped: 0, Failed: 0
[12:12:34 INFO]: [InventoryRollbackPlus] All tests passed successfully.

You may also include screenshots, logs, /timings links, /spark profiler links here.

Additional info:

Add any other context about the problem here. If not applicable just replace this line with N/A

[TechnicallyCoded]

Shulker boxes were added before 1.12 no?

[asdassafas]

Shulker boxes were added before 1.12 no?

Yes, it was added to the game in version 1.11. I wonder if there's any way to make this error disappear?