code: public Document toXml(InputStream json) throws IOException, NotImplemented {
          JsonReader reader = null;
          try {
              reader = new JsonReader(new InputStreamReader(json, "utf-8"));
              return parse(reader);
          } catch (UnsupportedEncodingException e) {
              throw new IllegalStateException(e);
          } finally {
              if (reader != null) reader.close();
              if (json != null) json.close();
          }
      }
docs: First element must be a document
  
  @param json JSON stream
  @return XML document