public Map<String, Object> walkFileNodePtr(FileNodePtr fileNodePtr,
                                               OneNotePropertyId parentPropertyId)
            throws IOException, TikaException, SAXException {
        if (fileNodePtr != null) {
            FileNode fileNode = fileNodePtr.dereference(oneNoteDocument);
            return walkFileNode(fileNode, parentPropertyId);
        }
        return Collections.emptyMap();
    }
Walk the file node pointer.

@param fileNodePtr The file node pointer.
@param parentPropertyId The PropertyId of the parent.
@return Returns a map of the main data.
@throws IOException Can throw these when manipulating the seekable byte channel.
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/onenote/OneNoteTreeWalker.java