Feign Client does not resolve Query parameter

As the recent(2019.04) open feign issue and spring doc say：

The OpenFeign @QueryMap annotation provides support for POJOs to be used as GET parameter maps.

Spring Cloud OpenFeign provides an equivalent @SpringQueryMap annotation, which is used to annotate a POJO or Map parameter as a query parameter map since 2.1.0.

You can use it like this:

    @GetMapping("user")
    String getUser(@SpringQueryMap User user);

public class User {
    private String name;
    private int age;
    ...
}

Working fine using @QueryMap

URL: /api/v1/task/search?status=PENDING&size=20&page=0

Map<String, String> parameters = new LinkedHashMap<>()
        parameters.put("status", "PENDING")
        parameters.put("size", "20")
        parameters.put("page", "0")
        def tasks = restClientFactory.taskApiClient.searchTasks(parameters)

Inside Client Interface

@RequestLine("GET /api/v1/task/search?{parameters}")
List<Task> searchTasks(@QueryMap Map<String, String> parameters)

It seems to be caused by a bug that is already opened - https://github.com/OpenFeign/feign/issues/424

Like in comments, you can define your own Param.Expander something like below as a workaround.

@RequestLine("GET /Groups?filter={roleName}")
String isValidRole(@Param(value = "roleName", expander = PrefixExpander.class) String roleName);

static final class PrefixExpander implements Param.Expander {
    @Override
    public String expand(Object value) {
        return "displayName+Eq+" + value;
    }
}

With Spring feign client below works fine :

@GetMapping("/Groups?filter=displayName+Eq+{roleName}")
    SCIMGroup isValidRole(@PathVariable(value = "roleName") String roleName);