code: @Nonnull
    public Sheet createNewSheet (@Nullable final String sName)
    {
      m_aLastSheet = sName == null ? m_aWB.createSheet () : m_aWB.createSheet (WorkbookUtil.createSafeSheetName (sName));
      m_nLastSheetRowIndex = 0;
      m_aLastRow = null;
      m_nLastRowCellIndex = 0;
      m_aLastCell = null;
      m_nMaxCellIndex = 0;
      return m_aLastSheet;
    }
docs: Create a new sheet with an optional name
  
  @param sName
  The name to be used. May be <code>null</code>.
  @return The created workbook sheet