message: testing: use Span safely in case of resize of underlying buffer
diff: @@ -279,13 +279,26 @@ TEST_F(ADIOS2_CXX11_API_Put, MultiBlockPutZeroCopySync)
  adios2::Variable<T> var = m_Io.DefineVariable<T>("var", m_Shape);
  MyDataView<T> myData(m_Selections);
  +#if 0
  + // keeping this as an example on how not to use Span
  for (int b = 0; b < myData.NBlocks(); ++b)
  {
  var.SetSelection(myData.Selection(b));
  auto span = engine.Put(var);
  myData.Place(b, span.data());
  }
  -
  +#else
  + std::vector<typename adios2::Variable<T>::Span> spans;
  + for (int b = 0; b < myData.NBlocks(); ++b)
  + {
  + var.SetSelection(myData.Selection(b));
  + spans.push_back(engine.Put(var));
  + }
  + for (int b = 0; b < myData.NBlocks(); ++b)
  + {
  + myData.Place(b, spans[b].data());
  + }
  +#endif
  for (int b = 0; b < myData.NBlocks(); ++b)
  {
  PopulateBlock(myData, b);
  