hasKey doesn't see the field in the response

Question

I have test:

   @Test
   public void sixTest() {
       FlowerList flowerList = new FlowerList();
       Specification.installSpec(Specification.requestSpec(), Specification.responseSpec());
       Response response = given()
                .when()
                .get("/api/unknown")
                .then()
                .log().all()
                .body("data.year", hasKey("2001"))
                .extract().response().as((Type) FlowerList.class);

I need to check that at least one year field contained the value 2001. But I get an exception:

Expected: map containing ["2001,"->ANYTHING]
  Actual: [2000, 2001, 2002, 2003, 2004, 2005]

What am I doing wrong? In theory hasKey should return a single value 2001

get:

{
    page: 1,
    per_page: 6,
    total: 12,
    total_pages: 2,
    data: [
    {
    id: 1,
    name: "cerulean",
    year: 2000,
    color: "#98B2D1",
    pantone_value: "15-4020"
    },
    {
    id: 2,
    name: "fuchsia rose",
    year: 2001,
    color: "#C74375",
    pantone_value: "17-2031"
    },
    ... 

Answer 1

The error message give you the answers

Expected: map containing ["2001,"->ANYTHING]
  Actual: [2000, 2001, 2002, 2003, 2004, 2005]

The actual result is an array, instead of a map. hence
Matchers.hasItems (match if Iterable has items)
should be used instead of
Matchers.hasKeys (match if the Map has key)

Another problem is, since year is Integer, 2001 should be the expected value instead of "2001".

So the assertion should be

.body("data.year", hasItems(2001))