code: public byte[] transform(String className, InputStream is) throws IOException, IllegalClassFormatException {
  
  		try {
  			
  			byte[] classBytes = readBytes(is);
  			
  			return transformer.transform(classLoader, className, null, null, classBytes);
  			
  		} finally {
  			if (is != null){
  				is.close();
  			}
  		}
  	}
docs: Transform a input stream.