Skip nullness check for Map-like return types of @BatchMapping methods

[iyanging]

The current implementation of checkDataFetcherNullness() only validates nullability for method return types, which fails to properly handle @BatchMapping methods that return Map<Parent, Field> (no other annotations).

As a workaround, I currently need to annotate @BatchMapping return types with @Nullable (e.g., @Nullable Map<Parent, Field>) to suppress these false positives.

Is there any plan to reduce these false positive warnings?

[bclozel]

@iyanging Sorry but this report isn't really actionable right now. You are mentioning false positives in schema reports and batch mapping controller methods without actually sharing them.

I have tried reproducing the problem with the following:

type Query {
	bookById(id: ID): Book
}
type Book {
	id: ID!
	title: String!
	author: Author
}
type Author {
	name: String!
}

@Controller
@NullUnmarked
static class BatchMappingBookController {

	@QueryMapping
	public Book bookById(String id) {
		return new Book("42", "Spring for GraphQL Book");
	}

	@BatchMapping
	public Mono<@NonNull Map<Book, Author>> author(List<Book> books) {
		return Mono.empty();
	}
}

@NonNull
record Book(String id, String title) {

}

@NonNull
record Author(String name) {

}

I am not getting any failure with the schema inspection report here.

Can you share more information? Ideally, you could share a minimal sample application that uses the latest Spring Boot 4.0.0-SNAPSHOT version.

[iyanging]

@bclozel
Thank you for your patience.

package com.example.spring_graphql_1334_mre;

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.graphql.data.method.annotation.Argument;
import org.springframework.graphql.data.method.annotation.BatchMapping;
import org.springframework.graphql.data.method.annotation.QueryMapping;
import org.springframework.stereotype.Controller;

import java.util.List;
import java.util.Map;

@NullMarked
@SpringBootApplication
@Controller
public class SpringGraphql1334MreApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringGraphql1334MreApplication.class, args);
    }

    @QueryMapping("bookById")
    public @Nullable Book demoList(@Argument @Nullable String id) {
        return new Book("1", "1");
    }

    @BatchMapping(typeName = "Book", field = "author")
    public Map<Book, Author> demoName(List<Book> parents) {
        return Map.of();
    }
//    @BatchMapping(typeName = "Book", field = "author")
//    public @Nullable Map<Book, Author> demoName(List<Book> parents) {
//        return Map.of();
//    }

    public record Book(String id, String title) {
    }

    public record Author(String name) {
    }
}