Upgraded Spring: org.springframework.web.client.UnknownContentTypeException: Could not extract response

Question

So I upgraded Spring from 2.1.15 to 2.2.8

I have @SpringBootTests where I make a rest template and make requests to localhost.

Full error is

org.springframework.web.client.UnknownContentTypeException: Could not extract response: no suitable HttpMessageConverter found for response type [class MyResponseClass] and content type [text/html;charset=utf-8]

My RestTemplateFactory

    public class RestTemplateFactory {

  public static RestTemplate getRestTemplate(String baseUrl) {
    RestTemplate restTemplate = new RestTemplate();

    restTemplate.setUriTemplateHandler(new DefaultUriBuilderFactory(baseUrl));
    restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());

    ResponseErrorHandler responseErrorHandler =
        new ResponseErrorHandler() {
          @Override
          public boolean hasError(ClientHttpResponse httpResponse) throws IOException {

            return (httpResponse.getStatusCode().series() == HttpStatus.Series.CLIENT_ERROR
                || httpResponse.getStatusCode().series() == HttpStatus.Series.SERVER_ERROR);
          }

          @Override
          public void handleError(ClientHttpResponse httpResponse) throws IOException {}
        };

    restTemplate.setErrorHandler(responseErrorHandler);

    return restTemplate;
  }

  public static RestTemplate getMultiTenantOAuthRestTemplate(
      String baseUrl, MockKeycloakUserDetails userDetails) {
    RestTemplate restTemplate = getRestTemplate(baseUrl);

    ClientHttpRequestInterceptor oauthInterceptor =
        (request, body, execution) -> {
          HttpHeaders headers = request.getHeaders();
          headers.add("Authorization", String.format("Bearer %s", getToken(baseUrl, userDetails)));
          headers.
          return execution.execute(request, body);
        };

    ClientHttpRequestInterceptor tenantInterceptor =
        (request, body, execution) -> {
          HttpHeaders headers = request.getHeaders();
          headers.add("Tenant-ID", userDetails.getTenant());
          return execution.execute(request, body);
        };

    restTemplate.setInterceptors(Arrays.asList(oauthInterceptor, tenantInterceptor));

    return restTemplate;
  }

How I use the rest template

def response = restTemplateForTenant(ACME_TENANT, acmeUser_1).getForEntity(url("ApiUrl"), MyResponseClass)

When I hit the API directly from my browser, the API seems to work fine. So it seems the configuration of my RestTemplate is a problem after upgrading?