Make RecordBuilder Jackson-friendly

[maff]

I'd like to use RecordBuilder in combination with Jackson using the builder for deserialization in order to leverage immutable collections and default values/initializers. This should work with a vanilla ObjectMapper instance without any custom mixins/configuration.

Problem description

Starting from the following test, it fails as type and properties is null as it does not use the builder at all (expected):

package com.example.model;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import io.soabase.recordbuilder.core.RecordBuilder;
import org.junit.jupiter.api.Test;

import java.util.Map;

import static org.assertj.core.api.Assertions.assertThat;

class RecordSerializationTest {

    @RecordBuilder
    @RecordBuilder.Options(
        useImmutableCollections = true
    )
    // @JsonDeserialize(builder = RecordSerializationTestMyTestModelBuilder.class)
    public record MyTestModel(
        String name,
        @RecordBuilder.Initializer("DEFAULT_TYPE") String type,
        Map<String, Object> properties
    ) {
        public static final String DEFAULT_TYPE = "dummy";
    }

    private final ObjectMapper objectMapper = new ObjectMapper();

    @Test
    void deserializingModelInvokesBuilder() throws JsonProcessingException {
        final var json = """
            {
              "name" : "test"
            }
            """;

        final var model = objectMapper.readValue(json, MyTestModel.class);
        assertThat(model.name()).isEqualTo("test");
        assertThat(model.type()).isEqualTo("dummy");
        assertThat(model.properties()).isNotNull().isEmpty();
    }
}

When uncommenting the @JsonDeserialize line, it tries to use the builder, but fails as Jackson's default implementation expects builder methods to start with with:

com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "name" (class com.example.model.RecordSerializationTestMyTestModelBuilder), not marked as ignorable (0 known properties: ])
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); line: 2, column: 13] (through reference chain: com.example.model.RecordSerializationTestMyTestModelBuilder["name"])

A solution to reconfigure Jackson to be aware of the builder using no prefix would be to annotate the builder class with @JsonPOJOBuilder(withPrefix = ""), but either I missed it or it is currently not possible to apply this to the generated builder class.

An ugly workaround is to enable public constructors on the builder class + to extend the generated builder with an annotated one (this makes the test pass):

    @RecordBuilder
    @RecordBuilder.Options(
        useImmutableCollections = true,
        publicBuilderConstructors = true
    )
    @JsonDeserialize(builder = MyTestModel.AnnotatedBuilder.class)
    public record MyTestModel(
        String name,
        @RecordBuilder.Initializer("DEFAULT_TYPE") String type,
        Map<String, Object> properties
    ) {
        public static final String DEFAULT_TYPE = "dummy";

        @JsonPOJOBuilder(withPrefix = "")
        public static class AnnotatedBuilder extends RecordSerializationTestMyTestModelBuilder {
        }
    }

Possible solutions

It would be great if RecordBuilder could expose a way to make this work nice together with Jackson without any workarounds or reconfiguration of the ObjectMapper. I'm aware that this affects interoperability with a third-party library but as this is a very common use-case (e.g. deserialization in Spring Boot controllers) it would be great to have built-in Jackson support directly in RecordBuilder.

I could imagine multiple ways of doing this:

• Add an option like addJsonPOJOBuilderAnnotation and add @JsonPOJOBuilder(withPrefix = "") to the generated builder if configured (potentially auto-enable this when Jackson is found on the classpath?).
• Kind of a workaround: provide a way to configure the setter prefix for builder methods to it can be set to with. I noticed this is already there, but not documented - created a small PR to update the docs in Add setterPrefix and enableGetters to options documentation #228. This works when setting it to with but it would be nicer to keep the builders as they are instead of introducing the prefix.
• Provide a way to specify arbitrary annotations which should be applied to the builder (given technical feasibility, as far as I've seen there have been similar discussions before).

[Randgalt]

Is this fixed by #228?

[maff]

#228 only added already existing options which were missing in the docs - it would only fix this issue when configuring record-builder to use with as setter prefix which is not ideal.

I think the easiest fix for this would be to add an option to add @JsonPOJOBuilder to the generated builders, setting the prefix to the setterPrefix configured for the record builder (could be omitted if the setterPrefix is with).

[maff]

@Randgalt I created a draft PR of the first option mentioned above in #232 - let me know if you'd be open to proceed adding this feature.