we should properly handle nulls

rest-api/src/main/java/lcsb/mapviewer/api/files/FileController.java

@@ -42,7 +42,7 @@ public class FileController extends BaseController {
 
   @PreAuthorize("@fileService.getOwnerByFileId(#id)?.login == authentication.name")
   @PostMapping(value = "/{id}:uploadContent")
-  public Map<String, Object> uploadContent(@PathVariable(value = "id") String id, @RequestBody byte[] data)
+  public Map<String, Object> uploadContent(@PathVariable(value = "id") Integer id, @RequestBody byte[] data)
       throws ObjectNotFoundException {
     return fileRest.uploadContent(id, data);
   }

rest-api/src/main/java/lcsb/mapviewer/api/files/FileRestImpl.java

@@ -60,7 +60,7 @@ public class FileRestImpl extends BaseRestImpl {
     return result;
   }
 
-  public Map<String, Object> uploadContent(String id, byte[] data) throws ObjectNotFoundException {
+  public Map<String, Object> uploadContent(Integer id, byte[] data) throws ObjectNotFoundException {
     int fileId = Integer.valueOf(id);
     UploadedFileEntry fileEntry = uploadedFileEntryDao.getById(fileId);
     if (fileEntry == null) {

service/src/main/java/lcsb/mapviewer/services/impl/FileService.java

@@ -21,20 +21,22 @@ public class FileService implements IFileService {
   }
 
   @Override
-  public UploadedFileEntry getById(int id) {
+  public UploadedFileEntry getById(Integer id) {
     return uploadedFileEntryDao.getById(id);
   }
 
   @Override
-  public User getOwnerByFileId(int id) {
-    UploadedFileEntry entry = uploadedFileEntryDao.getById(id);
-    if (entry != null && entry.getOwner() != null) {
-      //it's lazy initialized
-      entry.getOwner().getLogin();
-      return uploadedFileEntryDao.getById(id).getOwner();
-    } else {
-      return null;
+  public User getOwnerByFileId(Integer id) {
+    if (id != null) {
+      UploadedFileEntry entry = uploadedFileEntryDao.getById(id);
+      if (entry != null && entry.getOwner() != null) {
+        // it's lazy initialized
+        entry.getOwner().getLogin();
+        return uploadedFileEntryDao.getById(id).getOwner();
+      }
     }
+    return null;
+
   }
 
 }

service/src/main/java/lcsb/mapviewer/services/interfaces/IFileService.java

@@ -5,8 +5,8 @@ import lcsb.mapviewer.model.user.User;
 
 public interface IFileService {
 
-  UploadedFileEntry getById(int id);
+  UploadedFileEntry getById(Integer id);
 
-  User getOwnerByFileId(int id);
+  User getOwnerByFileId(Integer id);
 
 }