jsx-curly-spacing is inconsistent

[sbking]

All of the following are given as proper examples on standardjs.com:

function foo () { return true }
var obj = { 'key': 'value' }
import { myFunc1, myFunc2 } from 'module'
const { a: { b } } = foo
setTimeout(function () { alert('Hello world') })

And this produces no errors:

<div>{ this.someMethod() }</div>

But this produces an error:

 <div className={ foo }></div>

Why the inconsistent curly spacing?