duplicate child feature in relationwidget

beside add and delete child in the relationwidget of an attributeform, there is the new functionality duplicate feature. this duplicates the selected child feature and (if the child has a relation with the strength composition too) the grad child features.

src/gui/qgsrelationeditorwidget.cpp

@@ -436,20 +436,14 @@ void QgsRelationEditorWidget::linkFeature()
 
 void QgsRelationEditorWidget::duplicateFeature()
 {
-  QgsVectorLayer *layer = nullptr;
-
-  layer = mNmRelation.referencingLayer();
-
-  const QgsFeatureIds fids = mFeatureSelectionMgr->selectedFeatureIds();
+  QgsVectorLayer *layer = mRelation.referencingLayer();
 
-  for ( const QgsFeatureId &fid : fids )
+  QgsFeatureIterator fit = layer->getFeatures( QgsFeatureRequest().setFilterFids( mFeatureSelectionMgr->selectedFeatureIds() ) );
+  QgsFeature f;
+  while ( fit.nextFeature( f ) )
   {
     QgsVectorLayerUtils::QgsDuplicateFeatureContext duplicatedFeatureContext;
-    QgsFeature feature; //= layer->getFeature( fid );
-    QgsFeatureRequest freq;
-    freq.setFilterFid( fid );
-    layer->getFeatures( freq ).nextFeature( feature );
-    QgsVectorLayerUtils::duplicateFeature( layer, feature, QgsProject::instance(), 1, duplicatedFeatureContext );
+    QgsVectorLayerUtils::duplicateFeature( layer, f, QgsProject::instance(), 0, duplicatedFeatureContext );
   }
 }