code: public Response filenameHeader(String filename) {
          if (filename != null && !filename.isEmpty()) {
              header(HttpConstants.Header.CONTENT_DISPOSITION, "attachment; filename=\"" + filename + "\"");
          } else {
              header(HttpConstants.Header.CONTENT_DISPOSITION, "attachment; filename=\"\"");
          }
  
          return this;
      }
docs: Sets a filename header. It's a shortcut for {@code header(HttpConstants.Header.CONTENT_DISPOSITION, "attachment; filename=\"" + filename + "\"")}.
  
  @param filename
  @return