mapstruct is not able to look accessible constructor

Question

I'm getting this compilation error:

ReferenceGroup does not have an accessible constructor.

Here my mapper method:

    @Mapping(source = "groups", target = "nestedGroups")
    @Mapping(source = "references", target = "nestedReferences")
    net.gencat.transversal.espaidoc.domain.model.reference.ReferenceGroup toDomainModel(
            ReferenceGroup referenceGroup);

My related class is:

@Getter
public class ReferenceGroup {

    private final List<NestedGroup> nestedGroups;
    private final List<NestedReference> nestedReferences;

    @Builder
    private ReferenceGroup(List<NestedGroup> nestedGroups, List<NestedReference> nestedReferences) {

As you can see, ReferenceGroup class has no a public constructor. Instead of that, it has a lombok Builder class.

First question here, is why mapstruct is not detecting my Builder class. I've tested ReferenceGroupBuilder class visibility implementing a dump method inside the same mapper:

    default void sdf() {
        net.gencat.transversal.espaidoc.domain.model.reference.ReferenceGroup sdf = net.gencat.transversal.espaidoc.domain.model.reference.ReferenceGroup
                .builder().build();
    }

I've to say that another builder class exists: ReferenceGroupPathBuilder. Has it nothing to do?

My maven settings are:

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>${maven.compiler.source}</source>
                    <target>${maven.compiler.target}</target>
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.mapstruct</groupId>
                            <artifactId>mapstruct-processor</artifactId>
                            <version>${org-mapstruct.version}</version>
                        </path>
                        <path>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                            <version>${lombok.version}</version>
                        </path>
                        <dependency>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok-mapstruct-binding</artifactId>
                            <version>0.2.0</version>
                        </dependency>
                    </annotationProcessorPaths>
                    <compilerArgs>
        </compilerArgs>
                </configuration>