Spring Cloud Openfeign RequestInterceptor converts GET to POST when adding headers

I'm using FeignClient to call service and a RequestInterceptor to add a header, no body change, but it still convert GET to POST. Is there an alternative way to fix this other than using httpclient as backend of Feign?

@FeignClient(name = "admin", url = "${feign.client.config.admin.url:}")
public interface AdminService {
    @RequestMapping(value = "/api/users/{username:.+}", method = RequestMethod.GET)
    User getUser(@PathVariable("username") String username, @RequestParam("appName") String appName);
}

@Bean
public RequestInterceptor requestInterceptor() {
    return requestTemplate -> {
        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
        HttpServletRequest servletRequest = ((ServletRequestAttributes) requestAttributes).getRequest();
        String auth = servletRequest.getHeader("Authorization");

        if (StringUtils.isNotBlank(auth)) {
            requestTemplate.header("Authorization", servletRequest.getHeader("Authorization"));
        }
    };
}

After debugging and I found that it puts my "@PathVariable String username" into body which seems the reason of this happening.

Comment From: spencergibb

I think this may duplicate #123

Comment From: spring-projects-issues

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