Fix wrong url in filesystem response (when using proxies)

src/main/java/org/caosdb/server/resource/FileSystemResource.java

@@ -86,12 +86,11 @@ public class FileSystemResource extends AbstractCaosDBServerResource {
     }
 
     if (file.isDirectory()) {
-      String referenceString = getReference().toString();
-      if (!referenceString.endsWith("/")) {
-        referenceString = referenceString + "/";
-      }
+      String path = (specifier.endsWith("/") ? specifier : specifier + "/");
+      String referenceString = getUtils().getServerRootURI() + "/FileSystem/" + path;
+
       final Element folder = new Element("dir");
-      folder.setAttribute("path", (specifier.endsWith("/") ? specifier : specifier + "/"));
+      folder.setAttribute("path", path);
       folder.setAttribute("name", file.getName());
       folder.setAttribute("url", referenceString);