Bukkit

What steps will reproduce the problem?

Not exactly sure what this player did but he cast a bunch of spells in the same place.  Most of them are Protego spells but I also see Spongify and Mucus Ad Nauseum.  If I use the information spell, I can see most of them have negative time remaining.

I also see spewing in the logs:

[00:11:16] [Server thread/WARN]: [Ollivanders] Task #3 for Ollivanders v0.16 generated an exception
java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
    at me.cakenggt.Ollivanders.OllivandersSchedule.oeffectSched(OllivandersSchedule.java:85) ~[?
:?]
    at me.cakenggt.Ollivanders.OllivandersSchedule.run(OllivandersSchedule.java:47) ~[?:?]
    at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftTask.run(CraftTask.java:53) ~[craftbukkit.j
ar:git-Bukkit-b103841]
    at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftSchedule
r.java:349) [craftbukkit.jar:git-Bukkit-b103841]
    at net.minecraft.server.v1_9_R1.MinecraftServer.D(MinecraftServer.java:686) [craftbukkit.jar
:git-Bukkit-b103841]
    at net.minecraft.server.v1_9_R1.DedicatedServer.D(DedicatedServer.java:361) [craftbukkit.jar
:git-Bukkit-b103841]
    at net.minecraft.server.v1_9_R1.MinecraftServer.C(MinecraftServer.java:635) [craftbukkit.jar
:git-Bukkit-b103841]
    at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:539) [craftbukkit.j
ar:git-Bukkit-b103841]
    at java.lang.Thread.run(Thread.java:745) [?:1.7.0_101]

What is the expected output? What do you see instead?

That spells will expire and go away.

What version of the product are you using?

0.16

Do you have an error log of what happened?

See above, not clear if it is related

Please provide any additional information below.