Example not compiling due 'include/QtCore/qmetatype.h:766:23: error: invalid application of ‘sizeof’ to incomplete type ‘QSctpSocket’'

In file included from /home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qobject.h:54,
                 from /home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qabstractanimation.h:43,
                 from /home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/QtCore:6,
                 from /home/qt/RTA/qt5/6.0.0/gcc_64/include/QtWidgets/QtWidgetsDepends:3,
                 from /home/qt/RTA/qt5/6.0.0/gcc_64/include/QtWidgets/QtWidgets:3,
                 from /home/qt/RTA/qt5/Examples/Qt-6.0.0/network/multistreamserver/server.cpp:51:
/home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qmetatype.h: In instantiation of ‘struct QtPrivate::IsPointerToTypeDerivedFromQObject<QSctpSocket*>’:
/home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qmetatype.h:1017:60:   required from ‘struct QMetaTypeId<QSctpSocket*>’
/home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qmetatype.h:1037:10:   required from ‘struct QMetaTypeId2<QSctpSocket*>’
/home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qobject_impl.h:68:49:   required from ‘struct QtPrivate::TypesAreDeclaredMetaType<QtPrivate::List<QSctpSocket*, const QByteArray&> >’
/home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qobject.h:233:86:   required from ‘static QMetaObject::Connection QObject::connect(const typename QtPrivate::FunctionPointer<Func>::Object*, Func1, const typename QtPrivate::FunctionPointer<Func2>::Object*, Func2, Qt::ConnectionType) [with Func1 = void (Provider::*)(QSctpSocket*, const QByteArray&); Func2 = void (Server::*)(QSctpSocket*, const QByteArray&); typename QtPrivate::FunctionPointer<Func>::Object = Provider; typename QtPrivate::FunctionPointer<Func2>::Object = Server]’
/home/qt/RTA/qt5/Examples/Qt-6.0.0/network/multistreamserver/server.cpp:80:99:   required from here
/home/qt/RTA/qt5/6.0.0/gcc_64/include/QtCore/qmetatype.h:766:23: error: invalid application of ‘sizeof’ to incomplete type ‘QSctpSocket’
  766 |         static_assert(sizeof(T), "Type argument of Q_DECLARE_METATYPE(T*) must be fully defined");
      |                       ^~~~~~~~~
make[2]: *** [CMakeFiles/multistreamserver.dir/build.make:134: CMakeFiles/multistreamserver.dir/server.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:96: CMakeFiles/multistreamserver.dir/all] Error 2
make: *** [Makefile:149: all] Error