JPA entities are not constructed / recognized while loading data in test

Situation

I need to load some data into H2 database while testing phase. I placed SQL file data-h2.sql into src/test/resources folder. File is found and executed. But problem occurs with my entity classes.

I have this base entity class:

@MappedSuperclass
public abstract class BaseEntity implements Persistable<Long> {

  @Id
  @Column(name = "id", updatable = false, nullable = false)
  protected Long id;

  @Override
  public Long getId() {
    return id;
  }

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

  @Override
  public boolean isNew() {
    return this.id == null;
  }

}

and then concrete entities:

@Entity
@Table(name = "employees")
public class EmployeeEntity extends BaseEntity {

}

But while loading data in test entities are not constructed in "proper way", fields in base entity are not found. When I place these fields into concrete entities (e.g. Employee) everything works.

Column "id" not found; SQL statement: ....

Question

Is there some way how to solve this issue? What am I doing wrong?