Content of the "authors" field in the file "extension.json" in the code repository of 40 out of the 42 extensions with "code stewards" column set to "Unassigned" or "Under Review" on https://www.mediawiki.org/wiki/Developers/Maintainers as per 2019-08-09, except for LDAPAuthentication (lacks extension.json file) and wikidiff2 (no idea where to find its codebase).
Folks who once worked for WMF or WMDE (though not necessarily when they wrote that extension) are marked as such.