@Override
public FollowedArtifact followArtifact(User user, Artifact artifact) throws ServiceException, SecurityServiceException {
FollowedArtifact followedArtifact = getFollowedArtifact(user, artifact);
if (followedArtifact != null) {
throw new AlreadyFollowedArtifactException();
} else {
followedArtifact = new FollowedArtifact(artifact);
followedArtifactService.create(followedArtifact);
artifact.setFollowersCount(artifact.getFollowersCount() + 1);