Hibernate - JsonMappingException: failed to lazily initialize a collection of role when using @JsonIgnore

Question

I am using Java 1.7. I have a REST service, when I call it, I get the following error when it tries to map the Java object to JSON:

HTTP Status 500 - org.codehaus.jackson.map.JsonMappingException: failed to lazily initialize a collection of role: entity.Person.flightPreferences, no session or session was closed (through reference chain: com.nexct.auth.model.UserDetailsAndRoles["person"]->entity.Person["approver"]->entity.approval.AutoApprovalApproverConfiguration["approver"]->entity.Person["flightPreferences"])

and

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: entity.Person.flightPreferences, no session or session was closed

Code:

Person.java

@OneToMany(cascade = CascadeType.ALL)
@JsonIgnore
public List<TravellerFlightPreference> getFlightPreferences()
{
    return flightPreferences;
}

This post suggested to add @JsonIgnore, but I still get the error.

AuthenticationResource.java

@GET
@Path("/details")
@ApiOperation(value="Get user details for a user held in the jwt")
@ApiResponses({
        @ApiResponse(code=200, message="Success"),
        @ApiResponse(code=404, message="Not Found")
})
@Produces({ MediaType.APPLICATION_JSON })
public Response details(@HeaderParam("Authorization") String token, @Context HttpServletRequest request) {
    UserDetailsAndRoles userDetailsAndRoles = new UserDetailsAndRoles();
    String jwtToken = getJwtToken(token);
    String userName = jwtTokenUtil.extractUserName(jwtToken);
    Set<Role> memberRoles = new HashSet<>();
    Set<UserRole> userRoles = new HashSet<>();
    try {
        Member member = memberService.getMemberByUserName(userName);
        Person person = personService.getPersonEntityByMemberId(member.getId());
        //List<TravellerFlightPreference> travellerFlightPreferences = person.getFlightPreferences();
        List<Employee> employees = employeeService.findEmployeeByMemberId(member.getId());
        Contact contact = loginLocal.findContactMemberId(member.getId());
        List<Account> accounts = loginLocal.findAllAccountByMemberId(member.getId());
        memberRoles = roleManager.viewRolesAssignedToMember(new ViewRolesAssignedToMemberRequest(member.getId())).getRoles();
        for (Role role: memberRoles) {
            UserRole userRole = new UserRole();
            userRole.setId(role.getId());
            userRole.setName(role.getName());
            userRole.setDescription(role.getDescription());
            userRoles.add(userRole);
        }
        userDetailsAndRoles.setAccounts(accounts);
        userDetailsAndRoles.setContact(contact);
        userDetailsAndRoles.setEmployees(employees);
        userDetailsAndRoles.setMember(member);
        userDetailsAndRoles.setPerson(person);
        userDetailsAndRoles.setUserRoles(userRoles);
        //userDetailsAndRoles.setTravellerFlightPreferences(travellerFlightPreferences);
    } catch (MemberDoesNotExistException e) {
        logger.severe("Error getting member for userName: "+userName);
        e.printStackTrace();
        return Response.ok(null, "Error getting member for userName: "+userName+". "+e.getMessage()).build();
    }
    return Response.ok().entity(userDetailsAndRoles).build();
}

I think this error is because the flightPreferences are not loaded when the Person object is converted to JSON.

Question

• In the Person object, I do not tell Hibernate to Laizily load the flightPreferences, why are they not available?
• When I add the @JsonIgnore, why does it still get the error?