Wildcard is a valid Access-Control-Expose-Headers value

[jnfeinstein]

This check is dated. Wildcard is a valid configuration according to MDN and spec.

[rstoyanchev]

I think it's dated more than ill-informed. The code was written a year before the spec was changed it seems https://github.com/whatwg/fetch/issues/252.

[jhoeller]

@rstoyanchev since we have the same check in the older branches as well, I suppose this is a backport candidate? Even if it's not really a bug, depending on the impact of the fix, we could backport it as an enhancement to 5.2.x and 5.1.x at least.

[jnfeinstein]

@rstoyanchev fixed in original description. 👍