Fix copy drag and drop action (#5671)

Fixes #5653.

CHANGELOG.md

@@ -39,6 +39,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - After assigning an entry to a group, the item count is now properly colored to reflect the new membership of the entry. [#3112](https://github.com/JabRef/jabref/issues/3112)
 - The group panel is now properly updated when switching between libraries (or when closing/opening one). [#3142](https://github.com/JabRef/jabref/issues/3142)
 - We fixed an error where the number of matched entries shown in the group pane was not updated correctly. [#4441](https://github.com/JabRef/jabref/issues/4441)
+- We fixed an error where the wrong file is renamed and linked when using the "Copy, rename and link" action. [#5653](https://github.com/JabRef/jabref/issues/5653)
 - We fixed a "null" error when writing XMP metadata. [#5449](https://github.com/JabRef/jabref/issues/5449)
 - We fixed an issue where empty keywords lead to a strange display of automatic keyword groups. [#5333](https://github.com/JabRef/jabref/issues/5333)
 - We fixed an error where the default color of a new group was white instead of dark gray. [#4868](https://github.com/JabRef/jabref/issues/4868)

src/main/java/org/jabref/gui/externalfiles/ExternalFilesEntryLinker.java

@@ -1,6 +1,7 @@
 package org.jabref.gui.externalfiles;
 
 import java.nio.file.Path;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 
@@ -36,7 +37,7 @@ public Optional<Path> copyFileToFileDir(Path file) {
         if (firstExistingFileDir.isPresent()) {
             Path targetFile = firstExistingFileDir.get().resolve(file.getFileName());
             if (FileUtil.copyFile(file, targetFile, false)) {
-                return Optional.ofNullable(targetFile);
+                return Optional.of(targetFile);
             }
         }
         return Optional.empty();
@@ -71,7 +72,7 @@ public void moveFilesToFileDirAndAddToEntry(BibEntry entry, List<Path> files) {
     public void copyFilesToFileDirAndAddToEntry(BibEntry entry, List<Path> files) {
         for (Path file : files) {
             copyFileToFileDir(file)
-                    .ifPresent(copiedFile -> addFilesToEntry(entry, files));
+                    .ifPresent(copiedFile -> addFilesToEntry(entry, Collections.singletonList(copiedFile)));
         }
         renameLinkedFilesToPattern(entry);
     }