[KNOWAGE-8581] Fixed columns order into discovery widget excel export

(cherry picked from commit f35ad94)

knowagecockpitengine/src/main/java/it/eng/knowage/engine/cockpit/api/export/AbstractFormatExporter.java

@@ -269,6 +269,31 @@ protected JSONArray getTableOrderedColumns(JSONArray columnsNew, JSONArray colum
 			return new JSONArray();
 		}
 	}
+
+	protected JSONArray getDiscoveryOrderedColumns(JSONArray columnsNew, JSONArray columnsOld) {
+		JSONArray columnsOrdered = new JSONArray();
+		// new columns are in the correct order
+		// for each of them we have to find the correspondent old column and push it into columnsOrdered
+		try {
+			for (int i = 0; i < columnsNew.length(); i++) {
+
+				JSONObject columnNew = columnsNew.getJSONObject(i);
+
+				for (int j = 0; j < columnsOld.length(); j++) {
+					JSONObject columnOld = columnsOld.getJSONObject(j);
+					if (columnOld.getString("header").equals(columnNew.getString("name"))) {
+
+						columnsOrdered.put(columnOld);
+						break;
+					}
+				}
+			}
+			return columnsOrdered;
+		} catch (Exception e) {
+			LOGGER.error("Error retrieving ordered columns");
+			return new JSONArray();
+		}
+	}
 
 	protected String getTableColumnHeaderValue(JSONObject column) {
 		try {

knowagecockpitengine/src/main/java/it/eng/knowage/engine/cockpit/api/export/excel/ExcelExporter.java

@@ -877,6 +877,8 @@ public void fillSheetWithData(JSONObject dataStore, Workbook wb, Sheet sheet, St
 			if (widgetData.getString("type").equalsIgnoreCase("table") && widgetContent.has("columnSelectedOfDataset")) {
 				hiddenColumns = getHiddenColumnsList(columnSelectedOfDataset);
 				columnsOrdered = getTableOrderedColumns(columnSelectedOfDataset, columns);
+			} else if (widgetData.getString("type").equalsIgnoreCase("discovery") && widgetContent.has("columnSelectedOfDataset")) {
+				columnsOrdered = getDiscoveryOrderedColumns(columnSelectedOfDataset, columns);
 			} else {
 				columnsOrdered = columns;
 			}