Bukkit

What steps will reproduce the problem?
1.Normal use
2.MC 1.9
3.

What is the expected output? What do you see instead?
Console Error for Metrics

What version of the product are you using?
5.2

Do you have an error log of what happened?
[20:52:04] [Craft Scheduler Thread - 5/WARN]: Exception in thread "Craft Scheduler Thread - 5"
[20:52:04] [Craft Scheduler Thread - 5/WARN]: org.apache.commons.lang.UnhandledException: Plugin WarpSigns v5.2 generated an exception while executing task 9
    at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()[Lorg/bukkit/entity/Player;
    at com.huskehhh.warpsigns.metrics.Metrics.postPlugin(Metrics.java:364)
    at com.huskehhh.warpsigns.metrics.Metrics.access$500(Metrics.java:68)
    at com.huskehhh.warpsigns.metrics.Metrics$1.run(Metrics.java:256)
    at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftTask.run(CraftTask.java:71)
    at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
    ... 3 more

Please provide any additional information below.

I am seeing this problem with many plugins -
MC 1.9 has deprecated getOnlinePlayers()
I can't find it on Github so I can't fix it myself.