docs: @Override
      protected Collection<String> getChildren(final String relative) throws IOException {
  
          ZipFile zip = createZipFile();
          if (null == zip) {
              return Collections.emptyList();
          }
  
          Collection<String> children = new ArrayList<String>();
          Enumeration<? extends ZipEntry> entries = zip.entries();
          while (entries.hasMoreElements()) {
              ZipEntry entry = entries.nextElement();
              if (entry.isDirectory()) {
                  continue;
              }
              if ((relative.equals("")) || entry.getName().startsWith(relative + File.separator)) {
                  children.add(entry.getName());
              }
          }
  
          zip.close();
          return children;
      }