Make `JoinKeys` related changes due to refactor #371

All 197 tests pass, 1 skipped in 7s

    1 files ±0   24 suites ±0 7s ⏱️ -1s
198 tests ±0 197 ✔️ +3 1 💤 ±0 0 ❌ ±0
688 runs +4 687 ✔️ +7 1 💤 ±0 0 ❌ ±0

Results for commit ff818b4. ± Comparison against earlier commit 143e218.