code: protected FSDataInputStream decorateInputStream(FSDataInputStream inputStream, FileInputSplit fileSplit) throws Throwable {
  		// Wrap stream in a extracting (decompressing) stream if file ends with a known compression file extension.
  		InflaterInputStreamFactory<?> inflaterInputStreamFactory = getInflaterInputStreamFactory(fileSplit.getPath());
  		if (inflaterInputStreamFactory != null) {
  			return new InputStreamFSInputWrapper(inflaterInputStreamFactory.create(stream));
  		}
  
  		return inputStream;
  	}
docs: This method allows to wrap/decorate the raw {@link FSDataInputStream} for a certain file split, e.g., for decoding.
  When overriding this method, also consider adapting {@link FileInputFormat#testForUnsplittable} if your
  stream decoration renders the input file unsplittable. Also consider calling existing superclass implementations.
  
  @param inputStream is the input stream to decorated
  @param fileSplit   is the file split for which the input stream shall be decorated
  @return the decorated input stream
  @throws Throwable if the decoration fails
  @see org.apache.flink.api.common.io.InputStreamFSInputWrapper