[PL] Update for ptr version of getPropertyVec.

ProcessLib/GroundwaterFlow/GroundwaterFlowProcess.h

@@ -76,9 +76,9 @@ public:
                 getProcessVariables()[0].get().getNumberOfComponents(),
                 _integration_order);
 
-            boost::optional<MeshLib::PropertyVector<double>&> balance_pv(
+            auto* const balance_pv =
                 _balance_mesh->getProperties()
-                    .template getPropertyVector<double>(_balance_pv_name));
+                    .template getPropertyVector<double>(_balance_pv_name);
 
             balance.integrate(x, *balance_pv, *this);
             // post: surface_mesh has vectorial element property

ProcessLib/ProcessOutput.cpp

@@ -135,7 +135,7 @@ void doProcessOutput(
         std::string const& property_name, MeshLib::MeshItemType type)
     {
         // Get or create a property vector for results.
-        boost::optional<MeshLib::PropertyVector<double>&> result;
+        MeshLib::PropertyVector<double>* result = nullptr;
 
         auto const N = count_mesh_items(mesh, type);