Purpose of PluginApiImporter annotation

Hi,

RAML generator and some other generators define an API Importer class which extends com.eviware.soapui.plugins.ApiImporter and have com.eviware.soapui.plugins.PluginApiImporter annotation. I don't completely understand its purpose and I did not find documentation explaining what it does. Can somebody explain what functionality does the PluginApiImporter annotation provide? 

Thanks!