BuildIt Error Log

17:09:26 [INFO] Starting minecraft server version 1.6.2
17:09:26 [INFO] Loading properties
17:09:26 [INFO] Default game type: ADVENTURE
17:09:26 [INFO] Generating keypair
17:09:27 [INFO] Starting Minecraft server on 25.152.116.4:25565
17:09:27 [INFO] This server is running CraftBukkit version git-Bukkit-1.6.2-R0.1-b2838jnks (MC: 1.6.2) (Implementing API version 1.6.2-R0.1)
17:09:27 [SEVERE] Could not load 'plugins/BuildMyThing.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: bassintag/buildmything/common/BuildMyThing : 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_R2.CraftServer.loadPlugins(CraftServer.java:239)
	at org.bukkit.craftbukkit.v1_6_R2.CraftServer.<init>(CraftServer.java:217)
	at net.minecraft.server.v1_6_R2.PlayerList.<init>(PlayerList.java:56)
	at net.minecraft.server.v1_6_R2.DedicatedPlayerList.<init>(SourceFile:11)
	at net.minecraft.server.v1_6_R2.DedicatedServer.init(DedicatedServer.java:106)
	at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:391)
	at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)
Caused by: java.lang.UnsupportedClassVersionError: bassintag/buildmything/common/BuildMyThing : Unsupported major.minor version 51.0
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
	at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
	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:306)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:249)
	at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:173)
	... 9 more
17:09:27 [INFO] [Vault] Loading Vault v1.2.25-b333
17:09:27 [INFO] [ProtocolLib] Loading ProtocolLib v2.7.0
17:09:27 [INFO] [Vault] Enabling Vault v1.2.25-b333
17:09:27 [INFO] [Vault][Permission] SuperPermissions loaded as backup permission system.
17:09:27 [INFO] [Vault] Enabled Version 1.2.25-b333
17:09:27 [INFO] [ProtocolLib] Enabling ProtocolLib v2.7.0
17:09:27 [INFO] [ProtocolLib] Started structure compiler thread.
17:09:28 [INFO] Preparing level "Minigame Lobby"
17:09:28 [INFO] Preparing start region for level 0 (Seed: -8381725776445110272)
17:09:29 [INFO] Preparing spawn area: 28%
17:09:30 [INFO] Preparing spawn area: 57%
17:09:31 [INFO] Preparing spawn area: 80%
17:09:31 [INFO] Preparing start region for level 1 (Seed: -8381725776445110272)
17:09:32 [INFO] Preparing start region for level 2 (Seed: -8381725776445110272)
17:09:34 [INFO] Preparing spawn area: 81%
17:09:35 [INFO] Server permissions file permissions.yml is empty, ignoring it
17:09:35 [INFO] Done (7.056s)! For help, type "help" or "?"
17:09:54 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
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