extensions/markdown-language-features/src/markdownExtensions.ts/merge
	export function merge(a: MarkdownContributions, b: MarkdownContributions): MarkdownContributions {
		return {
			previewScripts: [...a.previewScripts, ...b.previewScripts],
			previewStyles: [...a.previewStyles, ...b.previewStyles],
			previewResourceRoots: [...a.previewResourceRoots, ...b.previewResourceRoots],
			markdownItPlugins: new Map([...a.markdownItPlugins.entries(), ...b.markdownItPlugins.entries()]),
		};
	}