extensions/markdown-language-features/src/markdownEngine.ts/MarkdownItEngine/_addLinkRenderer
class MarkdownItEngine:	private _addLinkRenderer(md: MarkdownIt): void {
		const original = md.renderer.rules.link_open;

		md.renderer.rules.link_open = (tokens: Token[], idx: number, options, env, self) => {
			const token = tokens[idx];
			const href = token.attrGet('href');
			// A string, including empty string, may be `href`.
			if (typeof href === 'string') {
				token.attrSet('data-href', href);
			}
			if (original) {
				return original(tokens, idx, options, env, self);
			} else {
				return self.renderToken(tokens, idx, options);
			}
		};
	}