Previously a default constructor was required for the result type
of mappedReduced() and filteredReduced(), even if a default value
was provided.
This patch fixes the problem.
The issue was in the ResultReporter type, that was calling
QList::resize() to adjust the size of expected reported results.
A default-value parameter was added to the class, so that
a corresponding overload of QList::resize could be invoked.
Task-number: QTBUG-88452
Change-Id: I51113753e314d76aa74d201b5a7e327a6ca75f47
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>