@Override
        public Document process(Document document) {
          processBlocks(document, true);
          processBlocks(document, false);
          return document;
        }
As we do custom include handling here, we have to reimplement all attribute handling we need.
So verify that only currently supported attributes are used.

@param reader The current reader
@param attributes The attributes used on the include directive
build-logic/asciidoc-extensions/src/main/java/org/spockframework/plugins/asciidoctor/IncludedSourceLinker.java