code: private Artifact getSourceArtifact() {
  		Artifact sourceArtifact = getArtifact(this.classifier);
  		return (sourceArtifact != null) ? sourceArtifact : this.project.getArtifact();
  	}
docs: Return the source {@link Artifact} to repackage. If a classifier is specified and
  an artifact with that classifier exists, it is used. Otherwise, the main artifact
  is used.
  @return the source artifact to repackage