public void addDescriptor(IArtifactDescriptor descriptor, IProgressMonitor monitor) {
   ((ArtifactDescriptor) descriptor).setRepository(this);
   artifactDescriptors.add(descriptor);
   keysToLocations.put(descriptor.getArtifactKey(), null);
 }
 public void addArtifact(IArtifactKey key, byte[] contents) {
   URI keyLocation = locationFor(key);
   keysToLocations.put(key, keyLocation);
   locationsToContents.put(keyLocation, contents);
 }