DYN-6515 OpenXML ExportXML Bug Fix (#16206)

Author: RobertGlobant20

src/Libraries/DSOfficeUtilities/OpenXmlHelper.cs

@@ -163,17 +163,21 @@ internal static bool Write(string filePath, string sheetName, object[][] data, i
                     }
 
                     Row row;
+                    //This case is when we need to append a new row at the end of the spreadsheet
                     if (rowsIndex >= rows.Count)
                     {
                         // Add a new row to the end
                         row = new Row() { RowIndex = currentRowIndex };
                         sheetData.AppendChild(row);
                     }
+                    //This case is when there are empty rows before or in between the populated rows
                     else if (rows[rowsIndex].RowIndex > currentRowIndex)
                     {
                         // Add a new row before this one
                         row = new Row() { RowIndex = currentRowIndex };
-                        sheetData.InsertBefore(rows[rowsIndex], row);
+
+                        //This is the method definition - InsertBefore(newChild, referenceChild), so we need to pass row as first argument
+                        sheetData.InsertBefore(row, rows[rowsIndex]);
                     }
                     else
                     {
@@ -608,6 +612,14 @@ private static void SetCellValue(object value, Cell cell, SharedStringTable shar
                 {
                     // The string is not in the table, so we add it
                     sharedStringTable.AppendChild(new SharedStringItem(new Text((string)value)));
+
+                    //Means that the current (row, column) is probably empty so we should start from 0
+                    if (sharedStringTable.Count == null)
+                    {
+                        sharedStringTable.Count = 0;
+                        sharedStringTable.UniqueCount = 0;
+                    }
+
                     index = (int)sharedStringTable.Count.Value;
                     // Yes, you need to update these manually
                     sharedStringTable.Count++;