code: public void putString(String strKey, String strValue)
      {
          if (this.getMessageFieldDesc(strKey) != null)
              this.getMessageFieldDesc(strKey).putString(strValue);
          else
              this.putNative(strKey, strValue);
      }
docs: Convert this external data format to the raw object and put it in the map.
  Typically overidden to return correctly converted data.