adapt-react results in 2 nested components as well.

Is the :rum/class metadata actually needed anywhere?

@tonsky Why is the boolean true value rendered as the empty string here: https://github.com/tonsky/rum/blob/gh-pages/src/rum/server_render.clj#L349 React complains about a difference between my server and client markup. It seems the client renders aria-hidden="true" and the server as aria-hidden="". Is this a bug?

Hmm, ok, looks like usually React renders true as "", but not in the aria-hidden case. I think this is another special case.