code: private void validateTimestampProtocol(String protocolString, String timestampFormat, String shape2) {
          if (!StringUtils.isNullOrEmpty(timestampFormat) && isNonJsonProtocol(protocolString)) {
              throw new IllegalArgumentException(String.format(
                  "Shape %s has timestamp format provided. Timestamp format for requests is not supported for xml, query or ec2 "
                  + "protocol",
                  shape2));
  
          }
      }
docs: Throw exception if timestamp is provided for non-json protocol