Setting a version for an artifact dependency in a Sling Provisioning file is optional.
By default an artifact without a defined version gets "LATEST" as version.
By defining an DependencyVersionResolver it is possible to plugin in an external dependency resolver
which decides which version to use if no version is given in the provisioning file.
If an exact version is given in the provisioning file this is always used.
artifact - Artifact without version (version is set to LATEST)
New version, or null if the version should not be changed