setCookie
Description
Adds a header to the response to request the update of the cookie with the given name on the client.
Use the deleteCookie directive to delete a cookie.
Example
final Route route = setCookie(HttpCookie.create("userName", "paul"), () ->
complete("The user was logged in")
);
// tests:
final HttpHeader expected = SetCookie.create(HttpCookie.create("userName", "paul"));
testRoute(route).run(HttpRequest.GET("/"))
.assertEntity("The user was logged in")
.assertHeaderExists(expected);