问如何允许用户在Select2上选择空字符串

EN

$("#e6").select2({
    placeholder: "Search for a movie",
    minimumInputLength: 1,
    ajax: { 
        url: "http://api.rottentomatoes.com/api/public/v1.0/movies.json",
        dataType: 'jsonp',
        data: function (term, page) {
            return {
                q: term, // search term
                page_limit: 10,
              };
        },
        results: function (data, page) { 
            return {results: data.movies};
        }
    },
 });