static boolean isDictionary(byte[] dictionary) {
    return (dictionary[0] == (byte) 0x37 && dictionary[1] == (byte) 0xA4
      && dictionary[2] == (byte) 0x30 && dictionary[3] == (byte) 0xEC);
  }
Returns dictionary and its ID number, useful for comparing to other dictionaries for equality
hbase-compression/hbase-compression-zstd/src/main/java/org/apache/hadoop/hbase/io/compress/zstd/ZstdCodec.java