obsolete .Highlights on SearchResponse, bad bad abstraction

Author: Mpdreamz

src/Nest/Search/Search/SearchResponse.cs

@@ -105,6 +105,7 @@ public class SearchResponse<T> : ResponseBase, ISearchResponse<T> where T : clas
 
 
 		private HighlightDocumentDictionary _highlights = null;
+		[Obsolete("This highlights by document id dictionary is the wrong abstraction in cases search can yield the same ids, scheduled for removal in 5.0 see #2168")]
 		/// <summary>
 		/// IDictionary of id -Highlight Collection for the document
 		/// </summary>