no setter methods in generated mapstruct implementation

I'm experimenting with mapstruct and follow this tutorial:

mapstruct tut

I have this entity:

@Entity
public class Company {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq_company")
    @SequenceGenerator(name = "seq_company", allocationSize = 1)
    @Column(nullable = false, updatable = false)
    private Long id;
    private String name;
    private String shortName;

    public Company() {
    }

    public Company(Long id, String name, String shortName) {
        this.id = id;
        this.name = name;
        this.shortName = shortName;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getShortName() {
        return shortName;
    }

    public void setShortName(String shortName) {
        this.shortName = shortName;
    }
}

And this is the simple dto:

public class CompanyDto {
    @JsonProperty("id")
    private Long id;
    @JsonProperty("name")
    private String name;
    @JsonProperty("shortName")
    private String shortName;
}

And here is the mapper interface:

@Mapper(componentModel = "spring")
public interface CompanyMapper {
    CompanyDto companyToCompanyDto(Company company);
    Company companyDtoToCompany(CompanyDto companyDto);
    List<CompanyDto> companiesToCompanyDtos(List<Company> companies);
}

I certanly oversee something, because there is no setters in the generated implementation, f. e.:

@Override
    public Company companyDtoToCompany(CompanyDto companyDto) {
        if ( companyDto == null ) {
            return null;
        }

        Company company = new Company();

        return company;
    }

What goes here wrong?