docs: public static BigInteger showNumberDialog(WindowBasedTextGUI textGUI, String title, String description, String initialContent) {
          TextInputDialog textInputDialog = new TextInputDialogBuilder()
                  .setTitle(title)
                  .setDescription(description)
                  .setInitialContent(initialContent)
                  .setValidationPattern(Pattern.compile("[0-9]+"), "Not a number")
                  .build();
          String numberString = textInputDialog.showDialog(textGUI);
          return numberString != null ? new BigInteger(numberString) : null;
      }