code: private ClassNode getClassNode(InputStream inputStream, int flags) {
          ClassNode cn = new ClassNode();
          try {
              ClassReader reader = new ClassReader(inputStream);
              reader.accept(cn, flags);
              inputStream.close();
          } catch (IOException e) {
              cn = null;
          }
          return cn;
      }
docs: Read an input stream to populate a {@code ClassNode}.
  
  @param inputStream the input stream containing the byte code
  @param flags flags to pass to the class reader
  
  @return the {@code ClassNode} or {@code null} if an error ocurred