[Overlay] add backdrop key

[giladgray]

fixes #2246

[reiv]

Missing a key here, too.

blueprint/packages/core/src/components/overlay/overlay.tsx

Lines 264 to 266 in 74cb9b6

	<CSSTransition classNames={transitionName} timeout={transitionDuration}>
	{decoratedChild}
	</CSSTransition>

[giladgray]

@reiv i thought so too, but the warning disappeared the moment i added just the one key in this PR.
i think React.Children.map is smart about keys and adds them itself?

[reiv]

@giladgray Looks like you're right -- if the Children.map callback returns a React element, it generates (or replaces) its key; the children that are mapped over already have keys of their own so it uses those (source). The docs don't mention it, however.

[blueprint-bot]

add backdrop key

Preview: documentation | landing | table