Fix: Export of ZIP entries in subdirectories

CityDoctorParent/CityDoctorModel/src/main/java/de/hft/stuttgart/citydoctor2/utils/ArchivePacker.java

@@ -35,6 +35,7 @@ public class ArchivePacker {
                 }
                 CityDoctorModel model = entry.getModel();
                 Path filePath = tmpDir.resolve(entry.getFullFileName());
+                Files.createDirectories(filePath.getParent());
                 model.saveAs(filePath.toString(), model.isValidated());
             }
             zipFolder(tmpDir.toFile(), outputPath.toFile());