PrimeFaces wizard component resets values in <h:select* /> components when form is submitted

Question

I have the following selectManyCheckbox inside a p:wizard component:

<p:wizard id="wizard">
  <p:tab id="page1" >
    <h:selectManyCheckbox 
      value="#{userController.user.roles}"
      layout="pageDirection" 
      converter="securityRoleConverter">

      <f:selectItems value="#{userController.rolesSelectMany}" />

    </h:selectManyCheckbox>
  </p:tab>

  <p:tab id="page2">
    <p:commandButton 
        value="Save"
        action="#{userController.create}"/>

  </p:tab>      
</p:wizard>

The roles property is an enum in the User class:

public class User {
  public enum SecurityRole {
    SENDER,
    RECEIVER,
    SUBSCRIBER,
    ADMIN;
  }

  String firstName;

  private List<SecurityRole> roles;

  public String getFirstName() {
      return firstName;
  }

  public void setFirstName(String firstName) {
      this.firstName = firstName;
  }

  public List<SecurityRole> getRoles() {
    if (roles == null) {
        roles = new ArrayList<SecurityRole>();
    }
    return roles;
  }

  public void setRoles(List<SecurityRole> roles) {
    this.roles = roles;
  }
}

The user controller is a JSF managed bean:

@ManagedBean
@ViewScoped
public class UserController {
  private User user;

 public User getUser() {
   return user;
 }

  public SelectItem[] getRolesSelectMany() {
    return JsfUtil.getSelectItems(Arrays.asList(SecurityRole.values()), false);
  }

  public void create() {
    // user is created here
  }

  @FacesConverter(value = "securityRoleConverter")
  public static class SecurityRoleConverter extends EnumConverter {

    public SecurityRoleConverter() {
        super(SecurityRole.class);
    }
  }
}

When I go from the first wizard page to the second page, the roles property is correctly set (verified in the debugger). However, when I click on the Save button on the 2nd wizard page, the roles property is set to an empty list (the corresponding setter is called). Other properties such as firstName remain. I noticed that this happens to every type of property, if it used inside a <h:select* /> component such as <h:selectManyCheckBox/>. This looks like a bug in the wizard component to me. Any ideas?

Thanks, Theo