Bug report: [Error SHULKER_BOX en 1.12.2]

[EsMokyGame]

Server details:

• Server version:
  This server is running Paper version git-Paper-1620 (MC: 1.12.2) (Implementing API version 1.12.2-R0.1-SNAPSHOT)

• IRP Version:
  [InventoryRollbackPlus]
  Plugin:
  Running InventoryRollbackPlus v1.7.3

Bug description:

This error is only generated when I start my server.

ERROR:

[10:48:12] [Server thread/INFO]: [InventoryRollbackPlus] Enabling InventoryRollbackPlus v1.7.3
[10:48:12] [Server thread/INFO]: [InventoryRollbackPlus] Attempting support for version: git-Paper-1620 (MC: 1.12.2)
[10:48:12] [Server thread/INFO]: [InventoryRollbackPlus] Using CraftBukkit version: v1_12_R1
[10:48:12] [Server thread/INFO]: [InventoryRollbackPlus] Inventory backup data is set to save to: YAML
[10:48:12] [Server thread/INFO]: [InventoryRollbackPlus] bStats are enabled
[10:48:12] [Server thread/ERROR]: [InventoryRollbackPlus] Test failed with exception: com.nuclyon.technicallycoded.inventoryrollback.util.test.SelfTest$$Lambda$2286/0x00007fa160dbfa98@20215938
java.lang.NoSuchFieldError: SHULKER_BOX
at com.nuclyon.technicallycoded.inventoryrollback.util.test.SelfTestSerialization.lambda$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(Unknown Source) [?:?]
[10:48:12] [Server thread/ERROR]: [InventoryRollbackPlus] Logs:
[10:48:12] [Server thread/INFO]: [InventoryRollbackPlus] Tests completed: 5, Skipped: 0, Failed: 0
[10:48:12] [Server thread/INFO]: [InventoryRollbackPlus] All tests passed successfully.