Make `JoinKeys` related changes due to refactor #533

All 197 tests pass, 1 skipped in 8s

    1 files ±0   24 suites ±0 8s ⏱️ -1s
198 tests ±0 197 ✔️ ±0 1 💤 ±0 0 ❌ ±0
688 runs ±0 687 ✔️ ±0 1 💤 ±0 0 ❌ ±0

Results for commit 6c5e8b9. ± Comparison against earlier commit ff818b4.