Getting error in serializing Stream<T> return type from http controller's method

[porechajp]

Expected Behavior

For the following record,

@Introspected
@Serdeable
public record Employee(String firstName, String lastName) {
}

and controller

@Controller("/api/employees")
public class EmployeeController {

    private static final List<Employee> data = List.of(new Employee("First","Last"));

    @Get
    public Stream<Employee> getAll(){
        return data.stream();
    }
}

The getAll method (called on HTTP GET /api/employees) should return a single element array of following,

[
 {"firstName": "First", "lastName":"Last"}
]

Actual Behaviour

Starting 4.3.0, the same method is failing with following exception,

Caused by: io.micronaut.serde.exceptions.SerdeException: Cannot serialize raw stream
	at io.micronaut.serde.support.serializers.StreamSerializer.createSpecific(StreamSerializer.java:37)
	at io.micronaut.serde.jackson.JacksonJsonMapper.writeValue(JacksonJsonMapper.java:174)
	at io.micronaut.serde.jackson.JacksonJsonMapper.writeValue0(JacksonJsonMapper.java:167)
	at io.micronaut.serde.jackson.JacksonJsonMapper.writeValue0(JacksonJsonMapper.java:162)
	at io.micronaut.serde.jackson.JacksonJsonMapper.writeValue(JacksonJsonMapper.java:248)
	at io.micronaut.http.netty.body.NettyJsonHandler.writeTo(NettyJsonHandler.java:161)

and on client side following is received,

{
    "_links": {
        "self": [
            {
                "href": "/api/employees",
                "templated": false
            }
        ]
    },
    "_embedded": {
        "errors": [
            {
                "message": "Internal Server Error: Error encoding object [java.util.stream.ReferencePipeline$Head@70693eaf] to JSON: Cannot serialize raw stream"
            }
        ]
    },
    "message": "Internal Server Error"
}

After some debugging, I concluded that this has probably got introduced due to commit : (Make NettyJsonHandler implement NettyBodyWriter)

Due to this change, the wrap method of RoutingInBoundHandler ,

    <T> NettyBodyWriter<T> wrap(MessageBodyWriter<T> closure) {
        if (closure instanceof NettyBodyWriter<T> nettyClosure) {
            return nettyClosure;
        } else {
            return new CompatNettyWriteClosure<>(closure);
        }
    }

started returning the same instance (as it now inherits from NettyBodyWriter) instead of CompatNettyWriteClosure.

I debugged this flow in 4.2.4 and 4.3.2 and in case of 4.2.4, since it creates CompatNettyWriteClosure, it ultimately results in to correct interpretation of Argument type in StreamSerializer's createSpecific method.

So in case of 4.2.4, Argument instance comes pointing to Stream,

whereas in case of 4.3.2, it points to Head,

Looks like unintentional effect.

If my understanding is incorrect, please let me know.

Steps To Reproduce

No response

Environment Information

Micronaut version 4.3.2 Oracle JDK 21 Windows 11

Example Application

No response

Version

4.3.2

[altro3]

looks like a bug in micronaut-serde. Try to use io.micronaut:micronaut-jackson-databind instead io.micronaut.serde:micronaut-serde-jackson. If all will be ok, then bug in micronaut-serialization

[porechajp]

@altro3 yes, micronaut-jackson-databind is working fine.