/// \brief Constructor.
 /// \param sendGrid   The grid that the data is attached to when sending.
 /// \param recvGrid   The grid that the data is attached to when receiving.
 /// \param sendState  The state where we will retieve the values to be sent.
 /// \param recvState The state where we will store the received values.
 BlackoilStateDataHandle(const Dune::CpGrid& sendGrid,
                         const Dune::CpGrid& recvGrid,
                         const BlackoilState& sendState,
                         BlackoilState& recvState)
     : sendGrid_(sendGrid), recvGrid_(recvGrid), sendState_(sendState), recvState_(recvState)
 {
     // construction does not resize surfacevol and hydroCarbonState. Do it manually.
     recvState.surfacevol().resize(recvGrid.numCells()*sendState.numPhases(),
                                   std::numeric_limits<double>::max());
     recvState.hydroCarbonState().resize(recvGrid.numCells());
 }