A DESCRIPTION OF THE PROBLEM :
If you are using special characters in a directory, the language encoding flag is not set, which typically results in an empty directory with broken encoding when looking at the archive with, for instance, 7zip, unzip or the Windows Explorer.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
$ zipdetails test.zip
[...]
0006 General Purpose Flag 0800
     [Bit 11] 1 'Language Encoding'
00E1 Filename 'äöß/'
[...]

ACTUAL -
$ zipdetails test.zip
[...]
0006 General Purpose Flag 0000
00E1 Filename 'äöß/'
[...]


---------- BEGIN SOURCE ----------
import java.net.URI;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.util.HashMap;
import java.util.Map;

class Test {
    static void main(String[] args) throws Exception {
            Map<String, Object> env = new HashMap<>();
            env.put("create", "true");
            URI uri = new URI("jar:file:/" + System.getProperty("user.home") + "/Desktop/test.zip");

            try (var fileSystem = FileSystems.newFileSystem(uri, env)) {
                var path = fileSystem.getPath("äöß/käfer.txt");
                Files.createDirectory(path.getParent());
                Files.writeString(path, "Test!");
            }
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Use:
env.put("encoding", "Cp437");

This works without the language encoding flag, but does not include as many characters, of course.

FREQUENCY : always