addArtifact method
Adds the given artifact to the band.
This method adds the provided artifact
to the list of artifacts in the band.
It also resets the cached rectangle, as the addition or removal of an artifact
can affect the overall layout and dimensions of the band.
Implementation
void addArtifact(final Artifact artifact) {
// reset the cached rectangle each time an artifact is added or removed
this.artifacts.add(artifact);
}