Update Preview Panel on Generate BibtexKey (#1355)

Fix for #1353
Use locking with lock try unlock
Some formatting
Encapsulate frame in getter

CHANGELOG.md

@@ -47,6 +47,7 @@ to [sourceforge feature requests](https://sourceforge.net/p/jabref/features/) by
 - Fixed [#1364](https://github.com/JabRef/jabref/issues/1364): Windows: install to LOCALAPPDATA directory for non-admin users
 - Fixed [#1365](https://github.com/JabRef/jabref/issues/1365): Default label pattern back to "[auth][year]"
 - Fixed [#796](https://github.com/JabRef/jabref/issues/796): Undoing more than one entry at the same time is now working
+- Fixed [#1353](https://github.com/JabRef/jabref/issues/1353): Fetch-Preview did not display updated BibTeX-Key after clicking on `Generate Now`
 
 ### Removed
 - Removed possibility to export entries/databases to an `.sql` file, as the logic cannot easily use the correct escape logic

src/main/java/net/sf/jabref/gui/DuplicateResolverDialog.java

@@ -68,7 +68,7 @@ public DuplicateResolverDialog(JabRefFrame frame, BibEntry one, BibEntry two, Du
     public DuplicateResolverDialog(ImportInspectionDialog dialog, BibEntry one, BibEntry two,
             DuplicateResolverType type) {
         super(dialog, Localization.lang("Possible duplicate entries"), true);
-        this.frame = dialog.frame;
+        this.frame = dialog.getFrame();
         init(one, two, type);
     }