code: public  String sessionOptionsToJson() {
          try {
              return JsonFormat.printer().print(protoBufConfigProto);
          } catch (Exception e) {
              e.printStackTrace();
          }
  
          return null;
      }
docs: Write out the session options used
  by this {@link GraphRunner}
  a s a  json string using the
  {@link JsonFormat}
  @return