"Unloading plugin JAR file lib/*.jar" spam in console

I've developed an Openfire plugin for Apple Push Notifications (for internal use only). I've used some external libraries and put them inside the lib folder of the JAR. The plugin works fine, but my Info-Log always get spammed with:

2014.01.23 15:52:24 org.jivesoftware.openfire.container.PluginClassLoader - Unloading plugin JAR file /usr/share/openfire/plugins/apnsplugin-1.0.0/lib/apns-0.2.3.jar

2014.01.23 15:52:24 org.jivesoftware.openfire.container.PluginClassLoader - Unloading plugin JAR file /usr/share/openfire/plugins/apnsplugin-1.0.0/lib/jackson-annotations-2.1.4.jar

2014.01.23 15:52:24 org.jivesoftware.openfire.container.PluginClassLoader - Unloading plugin JAR file /usr/share/openfire/plugins/apnsplugin-1.0.0/lib/jackson-core-2.1.4.jar

2014.01.23 15:52:24 org.jivesoftware.openfire.container.PluginClassLoader - Unloading plugin JAR file /usr/share/openfire/plugins/apnsplugin-1.0.0/lib/jackson-databind-2.1.4.jar

2014.01.23 15:52:24 org.jivesoftware.openfire.container.PluginClassLoader - Unloading plugin JAR file /usr/share/openfire/plugins/apnsplugin-1.0.0/lib/slf4j-api-1.7.2.jar

Do you have any idea why this happens?