Fix issue with missing year value in year column (#5197)

* Fix issue 5152, tooltip and icon added to group cell

* -fixed minor issue with style (empty line) in MainTableColumnFactory                                                                         -added key "Group color" into english language properties

* Fix issue of missing publication year of an entry when user  add content from IEEE library

Author: mmihuu

src/main/java/org/jabref/logic/importer/fetcher/IEEE.java

@@ -91,6 +91,7 @@ private static BibEntry parseJsonRespone(JSONObject jsonEntry, Character keyword
         entry.setField(StandardField.AUTHOR, authors.stream().collect(Collectors.joining(" and ")));
         entry.setField(StandardField.LOCATION, jsonEntry.optString("conference_location"));
         entry.setField(StandardField.DOI, jsonEntry.optString("doi"));
+        entry.setField(StandardField.YEAR,jsonEntry.optString("publication_year"));
         entry.setField(StandardField.PAGES, jsonEntry.optString("start_page") + "--" + jsonEntry.optString("end_page"));
 
         JSONObject keywordsContainer = jsonEntry.optJSONObject("index_terms");