I don't know if it's a mistake on my part or the plugin's part. EssentialsXMPP

[DrHase47]

Hey,
Is it a bug or a mistake on my part?

[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.ServiceDiscoveryManager
[04:56:34 WARN]: Nag author(s): '[snowleo, SupaHam, mdcfe]' of 'EssentialsXMPP v2.21.0-dev+154-667b0f7' about their usage of System.out/err.print. Please use your plugin's logger instead (JavaPlugin#getLogger).
[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.XHTMLManager
[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.muc.MultiUserChat
[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.bytestreams.ibb.InBandBytestreamManager
[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.bytestreams.socks5.Socks5BytestreamManager
[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.filetransfer.FileTransferManager
[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.LastActivityManager
[04:56:34 ERROR]: [EssentialsXMPP] [STDERR] Error! A startup class specified in smack-config.xml could not be loaded: org.jivesoftware.smackx.commands.AdHocCommandManager