Spring inject xml mapper into test that is used by default

I created a simple service that consumes xml (i generated model with jaxb from https://krankenhausstandorte.de/storage/templates/xsds/Standortverzeichnis.xsd)

Using WebClient i can easily read into desired Object:

public Standortverzeichnis getAll() {
    return this.client.get()
            .uri(config.getPathfull())
            .retrieve()
            .bodyToMono(Standortverzeichnis.class)
            .block(Duration.ofSeconds(config.getSecondsTimeout()));

So there seems to be an ObjectMapper in place that is deserializing to Standortverzeichnis.class.

How to get this mapper injected into a test? For json i just use @JsonTest and inject "ObjectMapper" into my test. But using this and reading xml i get:

Unexpected character ('<' (code 60)): expected a valid value (JSON String, Number, Array, Object or token 'null', 'true' or 'false')

So how to get the same mapper (with same configuration) injected into my test?