sorry for saying adapter at the end of my previous post, now it's correct.

What I mean is that it is the getItems method of the metadata adapter (see the MetadataProvider interface) that translates the group name into a list of items.

The LiteralBasedProvider is an implementation of MetadataProvider that splits the group name on the space character and use the results as items.

The FileBasedProvider is an implementation of MetadataProvider that appends ".items" to the group name and searches for a file with that name. It then reads a list of items from that file

So, you can implement your own getItems on your own MetadataProvider implementation with your own logic