protected int getCellBufSize() {
      int kvBufSize = KEY_VALUE_LEN_SIZE + keyLength + valueLength;
      if (includesTags() && tagsLength > 0) {
        kvBufSize += Bytes.SIZEOF_SHORT + tagsLength;
      }
      return kvBufSize;
    }
Copy the state from the next one into this instance (the previous state placeholder). Used to
save the previous state when we are advancing the seeker to the next key/value.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/RowIndexSeekerV1.java