code: public Element toElement(final ExcelDatastore datastore, final String filename) {
          final Element ds = getDocument().createElement("excel-datastore");
  
          ds.setAttribute("name", datastore.getName());
          if (!Strings.isNullOrEmpty(datastore.getDescription())) {
              ds.setAttribute("description", datastore.getDescription());
          }
  
          appendElement(ds, "filename", filename);
  
          if (datastore.getCustomColumnNames() != null && datastore.getCustomColumnNames().size() > 0) {
              final Element customColumnNamesElement = getDocument().createElement("custom-column-names");
              ds.appendChild(customColumnNamesElement);
  
              datastore.getCustomColumnNames()
                      .forEach(columnName -> appendElement(customColumnNamesElement, "column-name", columnName));
          }
  
          return ds;
      }
docs: Externalizes a {@link ExcelDatastore} to a XML element.
  
  @param datastore
  @param filename the filename/path to use in the XML element. Since the appropriate path will depend on the
  reading application's environment (supported {@link Resource} types), this specific property of the
  datastore is provided separately.
  @return