ECL folders are represented by the
IContentLibraryItem interface. When you open the ECL folder properties in the CME a MetadataXml object is retrieved. Reading the API documentation of the
IContentLibraryItem.MetadataXmlSchema methods it looks like ECL folders can have metadata.
When I implement the
MetadataXmlSchema, the CME only shows metadata on ECL file items (
IContentLibraryMultimediaItem), not on ECL folder items.
I did try this in debug, attached to Tcmservicehost. The methods mentioned above are not called when opening a folder, only when opening a file. So metadata is not implemented for folders, unless I missed something like
CanGetMetadata or so but I don't see that in the API doc.