Configuration fields in JIRA gadget

I’m trying to create a JIRA gadget and I need long text field (not textarea) on configuration screen. If I set class “long-field”, test field has only class “text” anaway. I don’t understand why. May be it’s possible bind showing configuration screen? Any suggestions?

                config: {
                    descriptor: function (args) {
                        const gadget = this;

                        return {
                            fields: [
                                    id: "testField",
                                    userpref: "testField",
                                    class: "long-field",
                                    label: "Test field:",
                                    type: "text",
                                    value: gadget.getPref("testField")
                    args: []