[06:35:11 WARN]: [OreRespawn] Task #2 for OreRespawn v1.0 generated an exception

java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextNode(Unknown Source) ~[?:1.8.0_45]

        at java.util.HashMap$KeyIterator.next(Unknown Source) ~[?:1.8.0_45]
        at me.BryceTheCoder.Main$1.run(Main.java:48) ~[?:?]
        at org.bukkit.craftbukkit.v1_8_R2.scheduler.CraftTask.run(CraftTask.java
:71) ~[spigot-1.8.3-R0.1-SNAPSHOT.jar:git-Spigot-2ec6f06-7722428]
        at org.bukkit.craftbukkit.v1_8_R2.scheduler.CraftScheduler.mainThreadHea
rtbeat(CraftScheduler.java:350) [spigot-1.8.3-R0.1-SNAPSHOT.jar:git-Spigot-2ec6f
06-7722428]
        at net.minecraft.server.v1_8_R2.MinecraftServer.A(MinecraftServer.java:7
20) [spigot-1.8.3-R0.1-SNAPSHOT.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.DedicatedServer.A(DedicatedServer.java:3
68) [spigot-1.8.3-R0.1-SNAPSHOT.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.MinecraftServer.z(MinecraftServer.java:6
51) [spigot-1.8.3-R0.1-SNAPSHOT.jar:git-Spigot-2ec6f06-7722428]
        at net.minecraft.server.v1_8_R2.MinecraftServer.run(MinecraftServer.java
:554) [spigot-1.8.3-R0.1-SNAPSHOT.jar:git-Spigot-2ec6f06-7722428]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]