code: private void createHierarchy() {
          for (Map.Entry<String, FileDescriptor> entry : containedFiles.entrySet()) {
              String relativePath = entry.getKey();
              FileDescriptor fileDescriptor = entry.getValue();
              int separatorIndex = relativePath.lastIndexOf('/');
              if (separatorIndex != -1) {
                  String parentName = relativePath.substring(0, separatorIndex);
                  FileDescriptor parentDescriptor = containedFiles.get(parentName);
                  if (parentDescriptor instanceof FileContainerDescriptor) {
                      ((FileContainerDescriptor) parentDescriptor).getContains().add(fileDescriptor);
                  }
              }
          }
      }
docs: Build the hierarchy of the container entries, i.e. add contains relations
  from containers to their children.