The standard, iirc (which Fabien explained to me long long ago) is to capitalize nouns and adjectives, but not verbs. So, `Validating a Hidden Response` would be correct. Two examples:

* sha: 1bedfa9832830012d9b83ae168957937808314bb
* sha: 15b6c3ca9deb107d811c2ab0c78cdd99baccb316

I've opened up a PR #3149 to clarify these.

So after that, are we happy with the header names here?