private boolean add() {
    // Validation:
    if (StringUtil.isEmpty(jtf_fileName.getText())) {
      JOptionPane.showMessageDialog(
          this, "Name must be present!", "Validation: name empty!", JOptionPane.ERROR_MESSAGE);
      jtf_fileName.requestFocus();
      return false;
    }

    // Read values:
    final String fileName = jtf_fileName.getText();
    final ContentType ct = jp_contentType.getContentType();
    final File file = new File(jtf_file.getText());
    final ReqEntityFilePart part = new ReqEntityFilePartBean(fileName, ct, file);

    // Trigger all listeners:
    for (AddMultipartPartListener l : listeners) {
      l.addPart(part);
    }

    // Clear:
    clear();

    // Focus:
    jb_file.requestFocus();

    return true;
  }