code: public static VoltTable fromJSONString(String json) throws JSONException, IOException {
          JSONObject jsonObj = new JSONObject(json);
          return fromJSONObject(jsonObj);
      }
docs: Construct a table from a JSON string. Only parses VoltDB VoltTable JSON format.
  
  @param json String containing JSON-formatted table data.
  @return Constructed <code>VoltTable</code> instance.
  @throws JSONException on JSON-related error.
  @throws IOException if thrown by our JSON library.