fix: check for formula cell type

Author: ReneSchroederLJ

backend/src/main/java/org/eclipse/tractusx/puris/backend/file/logic/service/ExcelService.java

@@ -470,7 +470,7 @@ private DataImportResult extractAndSaveDeliveries(Sheet sheet) {
                 }
                 deliveries.add(delivery);
             } catch (Exception e) {
-                errors.add(new DataImportError(rowIndex, List.of(e.getMessage() + " Further validations for this row are not possible.")));
+                errors.add(new DataImportError(rowIndex, List.of(e.getMessage() + " Further validations for this row are not possible.", row.toString())));
             }
         }
 
@@ -690,7 +690,7 @@ private List<String> extractHeader(Sheet sheet) {
     }
 
     private String getStringCellValue(Cell cell) {
-        return cell == null || cell.getCellType() == CellType.BLANK ? null : cell.getCellType() == CellType.STRING
+        return cell == null || cell.getCellType() == CellType.BLANK ? null : (cell.getCellType() == CellType.STRING || cell.getCellType() == CellType.FORMULA)
                 ? cell.getStringCellValue().trim()
                 : String.valueOf(cell.getNumericCellValue()).trim();
     }

docs/user/User_Guide.md

@@ -264,6 +264,10 @@ An Admin can upload data in this page. Once the file is uploaded, all existing d
 
 Right now, only files of type xlsx are supported.
 
+### Formula support
+
+The import feature evaluates formulas to dynamically calculate values. Due to technical limitations of the underlying Java library Apache POI not all functions are supported. You can find a list of supported functions int the [Apache POI documentation](https://poi.apache.org/components/spreadsheet/eval-devguide.html#appendixA).
+
 ### Import view
 
 ![Overview of the Import view](img/import_view.png)