bug with Form url encoded and a POJO with a list field

[sdelamo]

Issue description

With this record:

package com.example;

import io.micronaut.core.annotation.Introspected;
import io.micronaut.serde.annotation.Serdeable;

import java.util.List;

@Serdeable
public record QuestionSave(String question,
                           List<Long> usersId) {
}

and this controller:

package com.example;

import io.micronaut.http.MediaType;
import io.micronaut.http.annotation.Body;
import io.micronaut.http.annotation.Consumes;
import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Post;

@Controller("/questions")
public class QuestionController {
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    @Post("/save")
    QuestionSave save(@Body QuestionSave questionSave) {
        return questionSave;
    }
}

and this test fails when the list contains one item:

package com.example;

import io.micronaut.http.HttpRequest;
import io.micronaut.http.MediaType;
import io.micronaut.http.client.BlockingHttpClient;
import io.micronaut.http.client.HttpClient;
import io.micronaut.http.client.annotation.Client;
import io.micronaut.test.extensions.junit5.annotation.MicronautTest;
import org.junit.jupiter.api.Test;

import java.io.IOException;

import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import static org.junit.jupiter.api.Assertions.assertEquals;

@MicronautTest
class QuestionControllerTest {

    @Test ❌
    public void formWithListOfOneItem(@Client("/") HttpClient client) throws IOException {
        String body = "question=en+que+trabajas&usersId=1";
        String expectedJson = "{\"question\":\"en que trabajas\",\"usersId\":[1]}";
        assertWithBody(client, body, expectedJson);
    }

    @Test ✅
    public void formWithListOfMoreThanOne(@Client("/") HttpClient client) throws IOException {
        String body = "question=en+que+trabajas&usersId=1&usersId=2";
        String expectedJson = "{\"question\":\"en que trabajas\",\"usersId\":[1,2]}";
        assertWithBody(client, body, expectedJson);
    }

    private static void assertWithBody(HttpClient httpClient, String body, String expectedJson) throws IOException {
        BlockingHttpClient client = httpClient.toBlocking();
        String json = assertDoesNotThrow(() -> client.retrieve(HttpRequest.POST("/questions/save", body).contentType(MediaType.APPLICATION_FORM_URLENCODED_TYPE)));
        assertEquals(expectedJson, json);
    }
}

Both test pass when using Micronaut Jackson Databind.

[sdelamo]

this is now fixed in Micronaut Framework 4.2.0