16:15:28 [WARNING] Error enabling plugin NetworkManager
java.lang.UnsupportedClassVersionError: me/Dunios/NetworkManager/Main : Unsupported major.minor version 52.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:803)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at net.md_5.bungee.api.plugin.PluginClassloader.loadClass0(PluginClassloader.java:34)
    at net.md_5.bungee.api.plugin.PluginClassloader.loadClass(PluginClassloader.java:27)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at net.md_5.bungee.api.plugin.PluginManager.enablePlugin(PluginManager.java:304)
    at net.md_5.bungee.api.plugin.PluginManager.loadPlugins(PluginManager.java:212)
    at net.md_5.bungee.BungeeCord.start(BungeeCord.java:262)
    at net.md_5.bungee.BungeeCordLauncher.main(BungeeCordLauncher.java:55)
    at net.md_5.bungee.Bootstrap.main(Bootstrap.java:15)