FeignClientConfiguration.java

@Configuration
@RequiredArgsConstructor
public class FeignClientConfiguration {

private final ObjectFactory<HttpMessageConverters> messageConverters;

@Bean
public Encoder feignFormEncoder() {
    return new FormEncoder(new SpringEncoder(messageConverters));
}

/*@Bean
public Decoder feignDecoder() {
    MappingJackson2XmlHttpMessageConverter c = new MappingJackson2XmlHttpMessageConverter();
    ObjectFactory<HttpMessageConverters> objectFactory = () ->new HttpMessageConverters(c);
    return new ResponseEntityDecoder(new SpringDecoder(objectFactory));
}*/

}

ConsultaClient.java

@FeignClient(url = "${api.serpro.url}",
            name = "name",
            configuration = FeignClientConfiguration.class)
    public interface ConsultaClient {

    @PostMapping(consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE, produces = MediaType.APPLICATION_XML_VALUE)
    @Headers("Content-Type: application/x-www-form-urlencoded")
    List<DocumentoDTO> getData(ParamsDTO params);
}

下面的步骤序列帮助我解决了这个问题：
1 -将jackson-dataformat-xml依赖项添加到pom.xml

<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
    <version>2.14.1</version>
</dependency>

2 -在UserFeign.java中添加此自定义配置

@FeignClient(value = "SERVICE", url = "https://goog.dummyservice/api1/v1", decode404 = true, configuration = UserFeign.Configuration.class)
public interface UserFeign {

@GetMapping(value = "/docs/{profile}/{protocol}", consumes = MediaType.APPLICATION_XML_VALUE)
Object getUserData(@RequestHeader("Authorization") String token,
                     @PathVariable("profile") String profile,
                     @PathVariable("protocol") String protocol);

class Configuration {
    @Bean
    public Decoder feignDecoder() {
        return (response, type) -> {
            String bodyStr = Util.toString(response.body().asReader(Util.UTF_8));
            JavaType javaType = TypeFactory.defaultInstance().constructType(type);
            return new XmlMapper().readValue(bodyStr, javaType);
        };
    }
}

}