Bukkit

What steps will reproduce the problem?
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What is the expected output? What do you see instead?

What version of the product are you using? 9.5

Do you have an error log of what happened? yes

Please provide any additional information below.

Could not load 'plugins/EndSwear.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: me/FreeSpace2/EndSwear/EndSwear : Unsupported major.minor version 51.0
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:184)
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
    at org.bukkit.craftbukkit.v1_6_R3.CraftServer.loadPlugins(CraftServer.java:239)
    at org.bukkit.craftbukkit.v1_6_R3.CraftServer.<init>(CraftServer.java:217)
    at net.minecraft.server.v1_6_R3.PlayerList.<init>(PlayerList.java:56)
    at net.minecraft.server.v1_6_R3.DedicatedPlayerList.<init>(SourceFile:11)
    at net.minecraft.server.v1_6_R3.DedicatedServer.init(DedicatedServer.java:107)
    at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:393)
    at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.UnsupportedClassVersionError: me/FreeSpace2/EndSwear/EndSwear : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:80)
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:173)
    ... 9 more

Happens when a user posts a * in the chat. Or any other regex.