Fix import into current library issuing wrong message (JabRef#6266)

This change fixes JabRef#6266 in which an erroneous message "import cancelled" is displayed when importing into the current library. This fix was accomplished by modifying the parameter of the extends clause of the ImportEntriesDialog class to have a return type of Boolean rather than Void and making setResultConverter return false rather than null.

CHANGELOG.md

@@ -30,6 +30,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 - We fixed an issue with inconsistent capitalization of file extensions when downloading files [#6115](https://github.com/JabRef/jabref/issues/6115)
 - We fixed the display of language and encoding in the preferences dialog. [#6130](https://github.com/JabRef/jabref/pull/6130)
 - We fixed an issue where search full-text documents downloaded files with same name, overwriting existing files. [#6174](https://github.com/JabRef/jabref/pull/6174)
+- We fixed an issue where when importing into current library an erroneous message "import cancelled" is displayed even though import is successful. [#6266](https://github.com/JabRef/jabref/issues/6266)
 
 ### Removed
 

src/main/java/org/jabref/gui/importer/ImportEntriesDialog.java

@@ -44,7 +44,7 @@
 import org.controlsfx.control.CheckListView;
 import org.fxmisc.easybind.EasyBind;
 
-public class ImportEntriesDialog extends BaseDialog<Void> {
+public class ImportEntriesDialog extends BaseDialog<Boolean> {
 
     public CheckListView<BibEntry> entriesListView;
     public ButtonType importButton;
@@ -76,14 +76,14 @@ public ImportEntriesDialog(BibDatabaseContext database, BackgroundTask<ParserRes
         Button btn = (Button) this.getDialogPane().lookupButton(importButton);
         btn.disableProperty().bind(booleanBind);
 
-        setResultConverter(button -> {
+       setResultConverter(button -> {
             if (button == importButton) {
                 viewModel.importEntries(entriesListView.getCheckModel().getCheckedItems());
             } else {
                 dialogService.notify(Localization.lang("Import canceled"));
             }
 
-            return null;
+            return false;
         });
     }