Previous Button for AbstractWizard

How to make PreviousButton enabled?
I have to steps added to Wizard with Overriden methods:
First Step:

@NotNull
@Override
public Object getStepId() {
    return "firstStep";
}

@Nullable
@Override
public Object getNextStepId() {
    return "streamStep";
} 

Second step:

@NotNull
@Override
public Object getStepId() {
    return "streamStep";
}

@Nullable
@Override
public Object getNextStepId() {
    return null;
}

@Nullable
@Override
public Object getPreviousStepId() {
    return "firstStep";
}

Wizard

public class MyWizard extends AbstractWizard {
    public MyWizard(String title, Component dialogParent) {
        super(title, dialogParent);

    }

    public MyWizard(String title, @Nullable Project project) {
        super(title, project);
        init();
        getPreviousButton().setEnabled(true);
    }

    @Nullable
    @Override
    protected String getHelpID() {
        return null;
    }

}