- was trying out rules matching frequest PR comments (then)
- did a manual scan to find new instances of same issues
- "" -> `string.Empty`
- `String` -> `string` and similar
- fill empty XML doc elements
- ignored `JsonPatchDocument<TModel>`; just too many empty elements
- corrected missing / extra / out-of-order `<param>` descriptions
- `xml-docs-test` detects incorrect external references but not these local issues