@Override
    public String toString() {
        return "WebsocketConfig{"
                + "urls='"
                + urls
                + ", allowOrigin='"
                + allowOrigin
                + '}';
    }
@Test
    public void testToString() {
        String toString = "WebsocketConfig{urls='%s, allowOrigin='%s}";
        String expected = String.format(toString, URLS, ALLOW_ORIGIN);
        assertEquals(expected, websocketConfig.toString());
    }