no-array-index-key not working in React.Children.map

[himynameisdave]

Hi! This currently does not flag an error with no-array-index-key:

React.Children.map(this.props.children, (child, index) => {
    const className = classnames(
                        child.props.className,
                        `${this.props.transition}-finished`
                    );
    return React.cloneElement(child, { key: index, className });
});

Specifically, I would expect the key: index part to trigger the no-array-index-key warning.

(I realize that there is probably a better way to write this (ie: not using cloneElement), but I noticed this recently and saw that it didn't flag the warning.

---

PS: Thanks for the awesome ESLint plugin! 🎉 Can't wait for the next release!

[ljharb]

Sure, this seems like a reasonable addition.

[himynameisdave]

@ljharb thanks! I would actually like to try fixing this (as I use this plugin a lot, so it would be cool to contribute to it).