Start replacing python model

python/gui/auto_generated/processing/qgsprocessingtoolboxmodel.sip.in

@@ -394,6 +394,11 @@ If ``registry`` is specified then the model will show providers and algorithms
 from the given registry. If no registry is specified, then the processing
 registry attached to QgsApplication.processingRegistry() will be used
 by the model.
+%End
+
+    QgsProcessingToolboxModel *toolboxModel();
+%Docstring
+Returns the underlying source Processing toolbox model.
 %End
 
     void setFilters( QgsProcessingToolboxProxyModel::Filters filters );