Use closure actions, unless you need bubbling

I don't know what's wrong in my code. template/components/item.hbs:

<div class="form-group">
        <div class="col-sm-offset-2 col-sm-10">
            <button type="submit" class="btn btn-default"  disabled=></button>
        </div>
</div>

components/item.js:

import Component from '@ember/component';

export default Component.extend({
    buttonLabel: 'Save',

    actions: {
        buttonClicked(param) {
            this.sendAction('action', param);
        }
    }
});

Ember/library-app/app/components/item.js 8:13 error Use closure actions, unless you need bubbling ember/closure-actions