code: public CompressionCodec getCodec(Path file) {
      CompressionCodec result = null;
      if (codecs != null) {
        String filename = file.getName();
        String reversedFilename = new StringBuffer(filename).reverse().toString();
        SortedMap<String, CompressionCodec> subMap = 
          codecs.headMap(reversedFilename);
        if (!subMap.isEmpty()) {
          String potentialSuffix = subMap.lastKey();
          if (reversedFilename.startsWith(potentialSuffix)) {
            result = codecs.get(potentialSuffix);
          }
        }
      }
      return result;
    }
docs: Find the relevant compression codec for the given file based on its
  filename suffix.
  @param file the filename to check
  @return the codec object