Logging nested TMap / TSet in UE C++ without nested JoinBy

Development Programming & Scripting C++
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Problem: logging TMap<uint64, TSet> is still nested FString::JoinBy. If the value type later changes from TArray to TSet, every lambda signature has to change with it.

  UE_LOG(LogTemp, Display, TEXT("IdToValues: %s"), *FString::JoinBy(IdToValues, TEXT(","), [](const TPair<uint64, TSet<int32>>& Pair) {
    return FString::Printf(TEXT("{%llu:[%s]}"), Pair.Key, *FString::JoinBy(Pair.Value, TEXT(","), [](int32 Value) {
      return FString::Printf(TEXT("%d"), Value);
    }));
  }));

Strify is a UE 5.6+ C++ plugin: one call, compile-time overloads (SFINAE / if constexpr).

  UE_LOG(LogTemp, Display, TEXT("IdToValues: %s"), *UStrify::ToString(IdToValues, true));
  // second arg is Multilines

Not JSON. Not UPROPERTY reflection. Not Blueprint nodes.
LexToString covers scalars; it does not recurse containers or stale weak ptrs.
Add FString ToString() const on a struct or UObject and it is picked up the same way FVector already works.

Limits: UE 5.6+; empty containers stringify to “”; UObject without ToString() renders . Automation specs in the repo.