in nexus 2 uploading an artefact used to generate sha1 and md5 hash files for both the uploaded jar and the generated pom.
In nexus 3 these files are not created.
For compatibility reasons I would prefer to either:
- generate checksum files automatically
- make checksum file generation optional
- Hint that checksum files are not created 'automagically'
- Artefacts without valid checksum files will generate nasty warnings in build systems like maven or gradle