docs: private Optional<IncludeAllPageWithOutput> addOutputInformation(IncludeAllPage pages, FileResource baseResource, Path includeAllBasePath, Locale locale) {
  
      // depth = 0 is the file that has the include-all directive
      if (pages.depth == 0) {
        return of(new IncludeAllPageWithOutput(pages, pages.files.get(0), pages.files.get(0).getPath(), locale));
      }
  
      Path baseResourceParentPath = baseResource.getPath().getParent();
      
      Optional<FileResource> virtualResource = pages.files.stream().findFirst()
          .map(fr -> new VirtualPathFileResource(baseResourceParentPath.resolve(includeAllBasePath.relativize(fr.getPath()).toString()), fr));
  
      return virtualResource.map(vr -> {
        Path finalOutputPath = outputPathExtractor.apply(vr).normalize();
        return new IncludeAllPageWithOutput(pages, vr, finalOutputPath, locale);
      });
    }