HSEARCH400655: Invalid cardinality for projection on field

Question

We have 3 records as ProjectionConstructor to map the projections from ES backend

Doctor.java

public record Doctor(
    UUID id,
    String fullName,
    @ObjectProjection(includeDepth = 2) DoctorDetails doctorDetails,
    @ObjectProjection(includeDepth = 1) List<DoctorEspecialty> doctorEspecialties // **a Many To Many linking for `Especialties`
){}

DoctorEspecialty.java

@ProjectionConstructor
public record DoctorEspecialty(
    UUID id,
    @ObjectProjection(includeDepth = 1) Especialty especialtyCode,
    @ObjectProjection(includeDepth = 1) Doctor doctor) {}

Especialty.java

@ProjectionConstructor
public record Especialty(
    UUID id,
    String especialtyName,
    String localName
    Integer code,
    @ObjectProjection(includeDepth = 1) Language language) {}    

We are using the below code to retrieve the Doctor data and use mapstruct to map the data, ex: doctorMapper:

List<**.projection.Doctor> doctors = searchSession
            .search(Doctor.class)
            .select(**.projection.Doctor.class)
            .where((f, root) -> {
                root.add(f.matchAll());
                root.add(
                    // dynamic criteria based on request
            })
            .fetchHits(pageable.getPageNumber() * pageable.getPageSize(), pageable.getPageSize());

        return new PageImpl<DoctorDTO>(doctors.stream().map(doctorMapper::toDto).collect(Collectors.toList()), pageable, suppliers.size()); 

Getting below error:

• "status" : 500,
• "detail" : "HSEARCH400655: Invalid cardinality for projection on field 'doctorEspecialties.especialtyCode.id': the projection is single-valued, but this field is effectively multi-valued in this context, because parent object field 'doctorEspecialties' is multi-valued. Either call '.multi()' when you create the projection on field 'doctorEspecialties.especialtyCode.id', or wrap that projection in an object projection like this: 'f.object("doctorEspecialties").from().as(...).multi()'.",

It works fine if we use a composite record, but that leads to duplicate/redundent code in both projection-dtos and mapstruct mappers.

Thanks in advance for any help