Folders inside CompoundDocuments don't have the correct title

When creating a new compound document, folders contained in the compound, don't have a title (dc:title). It seems that this line https://github.com/nuxeo/nuxeo-compound-documents/blob/2021/nuxeo-compound-documents/src/main/java/org/nuxeo/compound/documents/CompoundDocumentServiceImpl.java#L122 is setting the dc:title to the wrong document:

• we should set the title to the doc variable, instead of compoundDoc