code: private static AssetLink createAssetLinkForImageAsset(long assetId) {
      AssetLink assetLink = new AssetLink();
      ImageAsset imageAsset = new ImageAsset();
      imageAsset.setAssetId(assetId);
      assetLink.setAsset(imageAsset);
      return assetLink;
    }
docs: Creates an {@link AssetLink} containing a {@link ImageAsset} with the specified asset ID.
  
  @param assetId ID of the image asset.
  @return a new {@link AssetLink}