Shiboken doesn't find contructors for forward declared Qt classes

I'm trying to generate bindings for a header with methods that use QTimeZone. QTimeZone is only forward-declared, not included in the header. Shiboken fails with

error: #error writeMinimalConstructorExpression: Could not find a minimal constructor for type 'const QTimeZone &'. This will result in a compilation error.

When I replace the forward-declaration with an include or include QTimeZone in the bindings.h it works fine.

The same issue can be observed with other Qt classes such as QJsonArray or QDateTime.

The failing code can be found at https://invent.kde.org/nicolasfella/kpublictransport/commits/bindings