How to serialize/deserialize request/response with snake case in javax.ws.rs.client.Client?

Question

I am trying to use javax.ws.rs.client.Client to invoke another service. I am not getting a proper response when there is a snake casing in the request/response. The code works fine when running on a server, but it's not when trying to invoke the service using the client in Junit.

Sample code:

@BeforeEach
  public void init() {
    wm1.stubFor(
        post("/customers")
            .willReturn(
                ok().withHeader("Content-type", "application/json")
                    .withBody(
                        """
                {"customer_name": "Test1",
                "customer_id": "71234"
                }""")));
  }

  @Test
  void buildClientTest() {
    Jsonb jsonB =
        JsonbBuilder.newBuilder()
            .withConfig(
                new JsonbConfig()
                    .withPropertyNamingStrategy(PropertyNamingStrategy.LOWER_CASE_WITH_UNDERSCORES))
            .build();

    Client client = ClientBuilder.newBuilder().register(jsonB).build();
    CustomerResponse customerResponse =
        client
            .target("http://localhost:8089/customers")
            .request(MediaType.APPLICATION_JSON)
            .header("accept", "application/json")
            .post(
                Entity.entity(buildRequest(), MediaType.APPLICATION_JSON), CustomerResponse.class);
    System.out.println("The response is " + customerResponse.toString());
    String customerId = customerResponse.getCustomerId();
    assertEquals("71234", customerId);
  }