Spring Boot @Mapping gives no read accessor error

public class MainDto {
    private ProjectDTO project;
    private TaskDTO task;
}

public class ProjectDTO {
    private UUID projectId;
    private Second second;
    private String name;
    private String desc;
}

public class SecondDTO {
    private UUID secondId;
    private String name;
    private String desc;
}

public class TaskDTO {
    private UUID taskId;
    private String taskName;
}

@Entity
public class ProjectEntity {
    @Id
    @Column(name = "project_id")
    private UUID projectId;

    @Column(name = "second_id")
    private UUID secondId;

    .... etc
}

@Entity
public class SecondEntity {
    @Id
    @Column(name = "second_id")
    private UUID secondId;

    .... etc
}

@Entity
public class TaskEntity {
    ...
}

public class main {
    ProjectEntity projEntity = ...
    SecondEntity sENtity = ...
    TaskEntity tEntity = ...
        ....
}

@Mapping(target = "project.second", source = "sEntity")
MainDTO mDTO(ProjectEntity projEntity, SecondEntity sEntity, TaskEntity tEntity);

@Mapping(target = "project", source = "projEntity")
@Mapping(target = "project.second", source = "sEntity")
MainDTO mDTO(ProjectEntity projEntity, SecondEntity sEntity, TaskEntity tEntity);

@Mapping(target = "project.description", source = "projEntity")
@Mapping(target = "project.second", source = "sEntity")
MainDTO mDTO(ProjectEntity projEntity, SecondEntity sEntity, TaskEntity tEntity);