public InputStream compress(File input) throws CompressException {
        FileInputStream inputStream = null;
        try {
            inputStream = new FileInputStream(input);
            return this.compress(inputStream);
        } catch (FileNotFoundException e) {
            throw new CompressException("File not found", e);
        } finally {
            IOUtils.closeQuietly(inputStream);
        }
    }
Returns a String with the default file extension for this compressor. For example, a zip-files default file
extension would be "zip" (without leading dot).

@return the default file extension
node/etl/src/main/java/com/alibaba/otter/node/etl/common/io/compress/impl/AbstractCompressor.java