Make `JoinKeys` related changes due to refactor #527

All 197 tests pass, 1 skipped in 6s

    1 files ±0   24 suites ±0 6s ⏱️ -1s
198 tests ±0 197 ✔️ ±0 1 💤 ±0 0 ❌ ±0
688 runs ±0 687 ✔️ ±0 1 💤 ±0 0 ❌ ±0

Results for commit ed7aa88. ± Comparison against earlier commit f258ae1.