@SuppressWarnings("WeakerAccess")
    public static void removePropertiesForPlugin(final String plugin) {
        getProperties().stream()
            .filter(systemProperty -> systemProperty.plugin.equals(plugin))
            .map(systemProperty -> systemProperty.key)
            .forEach(PROPERTIES::remove);
    }
Removes all the properties for a specific plugin. This should be called by a plugin when it is unloaded to
allow it to be added again without a server restart
@param plugin The plugin for which properties should be removed
xmppserver/src/main/java/org/jivesoftware/util/SystemProperty.java