/// <summary>
        ///     Adds currently selected assets to target package.
        /// </summary>
        /// <exception cref="ArgumentNullException"/>
        private static void AddSelectedAssets([NotNull] JEMAssetBuilderPackage package)
        {
            if (package == null)
            {
                throw new ArgumentNullException(nameof(package));
            }
            if (Selection.objects.Length == 0)
            {
                EditorUtility.DisplayDialog("Oops.", "To add new assets in to package, first you need to select the assets. (lul)", "Ok!");
                return;
            }

            foreach (var obj in Selection.objects)
            {
                if (package.Exist(obj))
                {
                    continue;
                }

                package.AddAsset(obj);
            }
        }