Unmarshalling of complex types in DBus 'v' variants not working

<method name="RequestResultList">
  <doc>
	<line>RequestResultList = This method gets the poi result list (e.g. after a Search/Scroll call)</line>
  </doc>
  <arg name="poiSearchHandle" type="u" direction="in">
	<doc>
	  <line>poiSearchHandle = poi search unique handle</line>
	</doc>
  </arg>
  <arg name="offset" type="q" direction="in">
	<doc>
	  <line>offset = starting offset of the newly requested list elements. If invalid (more that total list for instance) it starts from the begining.</line>
	</doc>
  </arg>
  <arg name="maxWindowSize" type="q" direction="in">
	<doc>
	  <line>maxWindowSize = maximum number of elements that should be returned as result</line>
	</doc>
  </arg>
  <arg name="attributes" type="as" direction="in">
	<doc>
	  <line>attributes = List of attributes name to retrieve. This is optional and the list could be empty.</line>
	</doc>
  </arg>
  <arg name="statusValue" type="q" direction="out">
	<doc>
	  <line>statusValue = enum(INVALID,NOT_STARTED,SEARCHING,FINISHED, ... )</line>
	</doc>
  </arg>
  <arg name="resultListSize" type="q" direction="out">
	<doc>
	  <line>resultListSize = Number of items of the results list</line>
	</doc>
  </arg>
  <arg name="resultListWindow" type="v" direction="out">
	<doc>
	  <line>For testing purposes returns '(ddi)' in the variant.</line>
	</doc>
  </arg>
  <error name="org.genivi.poiservice.poiSearch.Error.HandleNotAvailable">
	<doc>
	  <line>This error is generated if an application tries to use a poi search unique handle that is not available or not valid</line>
	</doc>
  </error>
  <error name="org.genivi.poiservice.poiSearch.Error.InvalidPoiAttribute">
	<doc>
	  <line>This error is generated if an application tries to get one or more invalid poi attributes.</line>
	</doc>
  </error>
</method>

namespace poiservice
{
  namespace poisearch
  {
    struct SLocation
    {
      double mLat;
      double mLon;
      qint32 mAlt;

      SLocation() : mLat(0.0), mLon(0.0), mAlt(0)
      {
      }
      bool operator==(const SLocation &other) const
      {
        return (mLat == other.mLat) && (mLon == other.mLon) && (mAlt == other.mAlt);
      }
    };

    QDBusArgument& operator<<(QDBusArgument& arg, const SLocation& location);
    const QDBusArgument& operator>>(const QDBusArgument& arg, SLocation& location);
  }
}    // namespace poiservice::poisearch

typedef QList<QString> TStringList;

Q_DECLARE_METATYPE(poiservice::poisearch::SLocation)

QDBusArgument& poiservice::poisearch::operator<<(QDBusArgument& arg, const SLocation& location)
{
  arg.beginStructure();
  arg << location.mLat << location.mLon << location.mAlt;
  arg.endStructure(); 
  return arg; 
}

const QDBusArgument& poiservice::poisearch::operator>>(const QDBusArgument& arg, SLocation& location)
{
  arg.beginStructure();
  arg >> location.mLat >> location.mLon >> location.mAlt;
  arg.endStructure();
  return arg; 
}

int metaTypeId = qDBusRegisterMetaType<SLocation>();

inline QDBusPendingReply<ushort, ushort, QDBusVariant> RequestResultList(uint poiSearchHandle, ushort offset, ushort maxWindowSize, const QStringList &attributes)
{
  QList<QVariant> argumentList;
  argumentList << QVariant::fromValue(poiSearchHandle) << QVariant::fromValue(offset) << QVariant::fromValue(maxWindowSize) << QVariant::fromValue(attributes);
  return asyncCallWithArgumentList(QLatin1String("RequestResultList"), argumentList);
}

void CPOIServicePOISearchWrapper::sltRequestResultList(quint32 poiSearchHandle, quint16 offset, quint16 maxWindowSize, TStringList attributes, quint16& outStatusValue, quint16& outResultListSize, QDBusVariant& outResultListWindow)
{
  QDBusPendingReply<ushort,ushort,QDBusVariant> reply = mProxy->RequestResultList(poiSearchHandle, offset, maxWindowSize, attributes);

  reply.waitForFinished();

  if (reply.isValid())
  {
    outStatusValue = reply.argumentAt<0>();
    outResultListSize = reply.argumentAt<1>();
    outResultListWindow = reply.argumentAt<2>();
  }
  else
  {
    QString exceptionMessage = QString::number(reply.error().type()) + " - " + reply.error().name() + " - " + reply.error().message();
    throw std::runtime_error(exceptionMessage.toStdString());
  }
}

  quint16 outStatusValue;
  quint16 outResultSize;
  QDBusVariant outVariant;
  QList<QString> stringList;
  // example call, we are interested in 'outVariant'
  mGeniviPoiSearch->sltRequestResultList(1, 0, 1000, stringList, outStatusValue, outResultSize, outVariant);

  QVariant variant = outVariant.variant();
  qDebug() << "Variant type: " << variant.type();
  // output of the above line: Variant type: QVariant::QPaintBufferCacheEntry 

  int userType = variant.userType();
  qDebug() << "Variant usertype: " << userType;
  // output of the above line: Variant usertype:  1028 

  if (variant.canConvert<poiservice::poisearch::SLocation>())
  {
    qDebug() << "CAN convert to SLocation";
  }
  else
  {
    // this code is executed, conversion fails. 
    qDebug() << "Can NOT convert to SLocation";
  }

  // also, this results in 'empty' struct:
  poiservice::poisearch::SLocation location = variant.value<poiservice::poisearch::SLocation>();