fix: use getSheet from SpreadsheetCommand to get the sheet

Author: ugur-vaadin

vaadin-spreadsheet-flow-parent/vaadin-spreadsheet-flow/src/main/java/com/vaadin/flow/component/spreadsheet/command/CellShiftValuesCommand.java

@@ -53,7 +53,7 @@ public CellReference getSelectedCellReference() {
             return selectedCellReference;
         } else {
             return new CellReference(
-                    spreadsheet.getActiveSheet().getSheetName(),
+                    getSheet().getSheetName(),
                     paintedCellRange.getFirstRow(),
                     paintedCellRange.getFirstColumn(), false, false);
         }

vaadin-spreadsheet-flow-parent/vaadin-spreadsheet-flow/src/main/java/com/vaadin/flow/component/spreadsheet/command/CellValueCommand.java

@@ -148,7 +148,7 @@ public void captureCellRangeValues(CellRangeAddress... cellRanges) {
 
     @Override
     public CellReference getSelectedCellReference() {
-        return new CellReference(spreadsheet.getActiveSheet().getSheetName(),
+        return new CellReference(getSheet().getSheetName(),
                 selectedCellRow, selectedcellCol, false, false);
     }
 
@@ -341,7 +341,7 @@ public Set<CellReference> getChangedCells() {
             if (o instanceof CellValue) {
                 CellValue cellValue = (CellValue) o;
                 changedCells.add(new CellReference(
-                        spreadsheet.getActiveSheet().getSheetName(),
+                        getSheet().getSheetName(),
                         cellValue.row, cellValue.col, false, false));
             } else {
                 CellRangeValue cellRangeValue = (CellRangeValue) o;

vaadin-spreadsheet-flow-parent/vaadin-spreadsheet-flow/src/main/java/com/vaadin/flow/component/spreadsheet/command/RowInsertOrDeleteCommand.java

@@ -44,7 +44,7 @@ public void execute() {
 
     @Override
     public CellReference getSelectedCellReference() {
-        return new CellReference(spreadsheet.getActiveSheet().getSheetName(),
+        return new CellReference(getSheet().getSheetName(),
                 row, 0, false, false);
     }