void clear() {
    for (Dictionary dictionary : dictionaries.values()) {
      dictionary.clear();
    }
    if (tagCompressionContext != null) {
      tagCompressionContext.clear();
    }
    if (valueCompressor != null) {
      valueCompressor.clear();
    }
  }
Read an integer from the stream in big-endian byte order.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/CompressionContext.java