code: private static String mapContent(DataHandler dh) {
          if (dh == null) {
              return "";
          }
          try {
              InputStream is = dh.getInputStream();
              String content = IOUtils.toString(is);
              is.close();
              return content;
          } catch (IOException e) {
              throw new RuntimeException(e);
          }
      }
docs: Map content.
  
  @param dh the data handler
  @return the string