deprecate: deprecate a public attribute

Author: javier-godoy

src/main/java/com/flowingcode/vaadin/addons/gridexporter/DocxStreamResourceWriter.java

@@ -167,6 +167,7 @@ private void fillData(XWPFTable table, XWPFTableCell dataCell, DataProvider<T, ?
             Iterator<Column<T>> iterator = exporter.getColumns().iterator();
             while (iterator.hasNext()) {
               iterator.next();
+              // preserve increment for deprecated attribute
               exporter.totalcells = exporter.totalcells + 1;
               currentRow.createCell();
             }

src/main/java/com/flowingcode/vaadin/addons/gridexporter/GridExporter.java

@@ -124,6 +124,8 @@ public class GridExporter<T> implements Serializable {
 
   SerializableSupplier<String> nullValueSupplier;
 
+  /** @deprecated. This attribute is incremented only when exporting DOCX, but it's never reset. */
+  @Deprecated(since = "2.5.0", forRemoval = true)
   public int totalcells = 0;
 
   private ButtonsAlignment buttonsAlignment = ButtonsAlignment.RIGHT;