Alternative-Class A

@Alternative
public class ImplementerA implements ImplementerIntf{

  @Override
  public String showImplementer() {
    return this.getClass().getName();
  }
} 

Alternative-Class B

@Alternative
public class ImplementerB implements ImplementerIntf{

  @Override
  public String showImplementer() {
    return this.getClass().getName();
  }
}

Alternative-Class C

@Alternative
public class ImplementerC implements ImplementerIntf{

  @Override
  public String showImplementer() {
    return this.getClass().getName();
  }
}

Alternative-Interface

public interface ImplementerIntf extends Serializable {
    public String showImplementer();
}