Error log

[21:16:15 INFO]: [RedProtect] Enabling RedProtect v7.7.2
[21:16:15 INFO]: [RedProtect] Server version: 1.15.2-R0.1-SNAPSHOT
[21:16:15 INFO]: [RedProtect] All configurations loaded!
[21:16:15 INFO]: [RedProtect] Language file loaded - Using: NO-NO
[21:16:15 INFO]: [RedProtect] Registering commands...
[21:16:15 INFO]: [RedProtect] Registering listeners...
[21:16:15 INFO]: [RedProtect] Essentials found. Hooked.
[21:16:15 INFO]: [RedProtect] WorldEdit found. Hooked.
[21:16:15 INFO]: [RedProtect] WorldGuard version 6 found. Hooked.
[21:16:15 INFO]: [RedProtect] Factions found. Hooked.
[21:16:15 INFO]: [RedProtect] - Loading world's regions...
[21:16:15 INFO]: [RedProtect] - Loading world_nether's regions...
[21:16:15 INFO]: [RedProtect] - Loading world_the_end's regions...
[21:16:15 INFO]: [RedProtect] Auto-save Scheduler: Saving file database every 60 minutes!
[21:16:15 INFO]: [RedProtect] There are 0 regions on (file) database!
[21:16:15 INFO]: [RedProtect] Dynmap found. Hooked.
[21:16:15 INFO]: [RedProtect] Loading dynmap markers...
[21:16:15 INFO]: [RedProtect] Dynmap markers loaded!
[21:16:15 INFO]: [RedProtect] Helper version: Latest
[21:16:15 INFO]: [RedProtect] Loading GuiFlags for 1.14+
[21:16:15 INFO]: [RedProtect] Metrics enabled! See our stats here: https://bstats.org/plugin/bukkit/RedProtect
[21:16:15 INFO]: [RedProtect] Loading API...
[21:16:15 INFO]: [RedProtect] API Loaded!
[21:16:15 INFO]:  _   _  _   _   _   _  _ _  _  _ _ _  __
[21:16:15 INFO]: |_| |_ | \ |_| |_| | |  |  |_ |   |    /
[21:16:15 INFO]: | \ |_ |_/ |   | \ |_|  |  |_ |_  |   /
[21:16:15 INFO]: » RedProtect v7.7.2 enabled
[21:16:15 INFO]:
[21:16:15 INFO]: [StructureBoxes] Enabling StructureBoxes v3.0
[21:16:15 INFO]: [StructureBoxes] A compatible version of WorldGuard has been detected
[21:16:15 INFO]: [StructureBoxes] A compatible version of Factions has been detected
[21:16:15 INFO]: [StructureBoxes] A compatible version of RedProtect has been detected
[21:16:15 ERROR]: Error occurred while enabling StructureBoxes v3.0 (Is it up to date?)
java.lang.UnsupportedOperationException: null
        at java.util.AbstractList.add(Unknown Source) ~[?:1.8.0_201]
        at java.util.AbstractList.add(Unknown Source) ~[?:1.8.0_201]
        at br.net.fabiozumbi12.RedProtect.Core.config.CoreConfigManager.addFlag(CoreConfigManager.java:261) ~[?:?]
        at br.net.fabiozumbi12.RedProtect.Bukkit.API.RedProtectAPI.addFlag(RedProtectAPI.java:245) ~[?:?]
        at io.github.eirikh1996.structureboxes.StructureBoxes.onEnable(StructureBoxes.java:219) ~[?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:263) ~[patched_1.15.2.jar:git-Paper-379]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:380) ~[patched_1.15.2.jar:git-Paper-379]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:483) ~[patched_1.15.2.jar:git-Paper-379]
        at org.bukkit.craftbukkit.v1_15_R1.CraftServer.enablePlugin(CraftServer.java:472) ~[patched_1.15.2.jar:git-Paper-379]
        at org.bukkit.craftbukkit.v1_15_R1.CraftServer.enablePlugins(CraftServer.java:386) ~[patched_1.15.2.jar:git-Paper-379]
        at net.minecraft.server.v1_15_R1.MinecraftServer.a(MinecraftServer.java:488) ~[patched_1.15.2.jar:git-Paper-379]        at net.minecraft.server.v1_15_R1.DedicatedServer.init(DedicatedServer.java:298) ~[patched_1.15.2.jar:git-Paper-379]
        at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:908) ~[patched_1.15.2.jar:git-Paper-379]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_201]