如何在ckeditor5中插入自定义HTML标签

import Plugin from '@ckeditor/ckeditor5-core/src/plugin';

export default class CustomTagPlugin extends Plugin {
    init() {
        const editor = this.editor;

        editor.commands.add('insertCustomTag', {
            execute() {
                editor.model.change(writer => {
                    const customTag = writer.createElement('customtag');
                    writer.append(customTag, editor.model.document.getRoot());
                });
            }
        });

        editor.ui.componentFactory.add('insertCustomTag', locale => {
            const view = new ButtonView(locale);

            view.set({
                label: 'Insert Custom Tag',
                icon: '<svg>...</svg>',
                tooltip: true
            });

            view.on('execute', () => {
                editor.execute('insertCustomTag');
            });

            return view;
        });
    }
}