Exception occurs while parsing seemingly valid XML in Spring’s Web Client [closed]

The problem is that I’m trying to request some API, and it’s response body has xml content that is for some reason not being parsed at all. You may skip ahead by not double-checking whether I matched the elements’ names in xml correctly according to the target class, because I’m pretty sure this is not the problem
Here’s an example response:

<?xml version="1.0" encoding="utf-8"?><OperationStateResponse xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://merchant.roboxchange.com/WebService/"><Result><Code>0</Code></Result><State><Code>10</Code><RequestDate>2023-09-03T22:34:33.6440213+03:00</RequestDate><StateDate>2023-09-01T15:53:38.1766667+03:00</StateDate></State><Info xsi:type="OperationInfoExt"><IncCurrLabel>BankCardPSBR</IncCurrLabel><IncSum>100.000000</IncSum><IncAccount>553691******5490</IncAccount><PaymentMethod><Code>BankCard</Code><Description>Банковской картой</Description></PaymentMethod><OutCurrLabel>BNR</OutCurrLabel><OutSum>100.000000</OutSum><OpKey>0296FAD0-7D7B-4DC0-99FE-A6064335A29C-Rf4RYsTRWZ</OpKey></Info><UserFields /></OperationStateResponse>

This is unformatted version, and there’s a formatted one:

<?xml version="1.0" encoding="utf-8"?>
<OperationStateResponse xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://merchant.roboxchange.com/WebService/">
    <Result>
        <Code>0</Code>
    </Result>
    <State>
        <Code>10</Code>
        <RequestDate>2023-09-03T22:34:33.6440213+03:00</RequestDate>
        <StateDate>2023-09-01T15:53:38.1766667+03:00</StateDate>
    </State>
    <Info xsi:type="OperationInfoExt">
        <IncCurrLabel>BankCardPSBR</IncCurrLabel>
        <IncSum>100.000000</IncSum>
        <IncAccount>553691******5490</IncAccount>
        <PaymentMethod>
            <Code>BankCard</Code>
            <Description>Банковской картой</Description>
        </PaymentMethod>
        <OutCurrLabel>BNR</OutCurrLabel>
        <OutSum>100.000000</OutSum>
        <OpKey>0296FAD0-7D7B-4DC0-99FE-A6064335A29C-Rf4RYsTRWZ</OpKey>
    </Info>
    <UserFields />
</OperationStateResponse>

In order to make this xml decodable into an object of my class, I used annotations from jakarta.xml.bind.annotation, such as @XmlRootElement. Here’s the gist of the class:

@XmlRootElement(name = "OperationStateResponse", namespace = "http://merchant.roboxchange.com/WebService/")
@NoArgsConstructor
public class OperationStateResponseBody implements Serializable {

    private Result result;

    private State state;

    @XmlElement(name = "Result")
    public Result getResult() {
        return this.result;
    }

    @XmlElement(name = "State")
    public State getState() {
        return this.state;
    }
    
    public static class State {
        ...
        // fields declared in the same manner as in the outer class
    }

    public static class Result {
        ...
        // fields declared in the same manner as in the outer class
    }

    // other not related stuff

}

What I invite you to notice is that I’ve added the namespace parameter to the @XmlRootElement annotation. Without it, no exception occurs, but the mapped response object is empty (fields are null). On top of that, if you follow the link, you’re gonna see that it gives an 403, what I think might be the problem here.
If I remove the parameter, I receive this error:

Caused by: org.springframework.core.codec.DecodingException: Could not unmarshal XML to class ru.kotomore.excursionapi.services.dto.OperationStateResponseBody
Caused by: jakarta.xml.bind.UnmarshalException: null
Caused by: com.sun.istack.SAXParseException2: unexpected element (uri:"http://merchant.roboxchange.com/WebService/", local:"OperationStateResponse"). Expected elements are <{}OperationStateResponse>

So what I’ve tried doing is:

1. Removing namespace parameter in @XmlRootElement annotation, which didn’t give desired outcome. Exception gone, but mapped object is empty
2. Changing @XmlRootElement annotation and all related ones to @Jackson… analogies. This way web client fails to recognize the target class as mappable at all. The reason is that apparently Spring does not support @Jackson… annotations in Spring (I am not stating this, but that’s my take that I’ve read from some other answer on Stackoverflow).

I’m guessing there has to be some way of simply ignoring the namespace given in the xml, but of course I don’t know whether it’s the case. I’ve been scratching my head all day long trying to solve this problem, it’s the last step to have my job project done, please help 🙁

EDIT:
Sorry, forgot to add the web client request code:

webClient.get()
                     .uri(uriBuilder -> uriBuilder.scheme(HttpScheme.HTTPS.toString())
                                                  .host("auth.robokassa.ru")
                                                  .path("/Merchant/WebService/Service.asmx/OpStateExt")
                                                  .queryParam(
                                                          "MerchantLogin",
                                                          paymentServiceConfigurationProperties.getMerchantName())
                                                  .queryParam("invoiceID", invoice.getId())
                                                  .queryParam("Signature", invoice.getSignature2())
                                                  .build())
                     .accept(MediaType.TEXT_XML)
                     .retrieve()
                     .bodyToMono(OperationStateResponseBody.class)
                     .subscribe(r -> invoiceStatusHandler(invoice, r));