Some best practice Java libraries like org.apache.commons.lang, client, beanutils etc are available as part of the server and client install in the rcp/eclipse/plugins folder.
But because they're not in the shared/eclipse/plugins folder, they cannot be used out-of-the-box with XPages. You need to either set them up as a plugin, move them to the relevant folder on all servers and developers' PCs, or manually copy the JAR files into each NSF and add to the build path.
None of these steps is unique because:
It would be better to have more of these best practice JAR files in the shared/ecipse/plugin folder. Having the latest versions would be even better. It would be great too to have additional best practice JAR files there for common functionality like Apache POI for exporting to Excel etc, iText for PDF generation, possible Apache Jersey for better standard REST service integration.
The folders of plugins for DOTS pick up from a separate area, so it would be best to review what's there as well to ensure it best supports DOTS users.
This would benefit not only XPage and DOTS developers, but also generic Java developers.