When using config-magnolia.js file for CKEditor it is not loaded properly due to magnoliaFileBrowser plugin not found. It seems that it is not included since magnolia 5.7.

Steps to reproduce it in demoauthor:

1. Configure a richtextfield within a form using configJsFile = /.resources/ckeditor/config-magnolia.js
2. Open the corresponding dialog to verify that it is not loaded correctly.

PM com.vaadin.server.VaadinServlet serveStaticResourcesInVAADIN
INFORMATION: Requested resource [/VAADIN/widgetsets/info.magnolia.widgetset.MagnoliaProWidgetSet/ckeditor/plugins/magnoliaFileBrowser/plugin.js] not found from filesystem or through class loader. Add widgetset and/or theme JAR to your classpath or add files to WebContent/VAADIN folder.

Debugging it, you can see that there is no js/fileBrowser/plugin.js file

Repeat the steps in Magnolia 5.6.X and check that it is loaded correctly.