docs: public BigDecimal getBigDecimal (int index) throws JSONException {
          Object object = this.get(index);
          BigDecimal val = JSONObject.objectToBigDecimal(object, null);
          if(val == null) {
              throw new JSONException("JSONArray[" + index +
                      "] could not convert to BigDecimal ("+ object + ").");
          }
          return val;
      }