OptionalcompareFor a given AssetArtifactFragment, checks whether the expected category can be extracted from it. If not,
null is returned, meaning that this artifact is not a candidate.
Maps the given ArtifactCandidate to an AssetArtifact.
Checks whether the given address is suited for an artifact candidate.
Comparison function for two candidates. Is used by the ArtifactMapper when there are multiple candidates, if implemented, otherwise ArtifactMapper.compareCandidatesByDate is used.