message: introducing constructor to initialize metadata as empty as it fails in case of clone when metadata is undefined.
diff: @@ -7,6 +7,10 @@ export class ArtifactItem {
  lastModified: Date;
  metadata: { [key: string]: string }
  + constructor() {
  + this.metadata = {};
  + }
  +
  public static clone(item: ArtifactItem): ArtifactItem {
  var clonedItem = new ArtifactItem();
  clonedItem.itemType = item.itemType;
  