private static String toString(List<MemoryBuffer> data) {
        String s = "";
        for (MemoryBuffer buffer : data) {
          s += buffer + ", ";
        }
        return s;
      }
Gets the end offset of the current row, or -1 if unknown.
llap-server/src/java/org/apache/hadoop/hive/llap/io/encoded/SerDeEncodedDataReader.java