com.fasterxml.jackson.databind.JsonMappingException: object is not an instance of declaring class

I have a CookingEvent.class which is a subclass of Event.class and hibernate inheritance strategy is @Inheritance(strategy=InheritanceType.JOINED) . when i am trying to send a List objects as a get response .I am getting below Exception

2016-08-25 11:49:22.351 ERROR 11944 --- [nio-8189-exec-1] o.a.c.c.C.[.[.[/].[servletContainer] : Servlet.service() for servlet [servletContainer] in context with path [] threw exception [org.glassfish.jersey.server.ContainerException: com.fasterxml.jackson.databind.JsonMappingException: object is not an instance of declaring class (through reference chain: java.util.ArrayList[0]->Object[]["eventId"])] with root cause

java.lang.IllegalArgumentException: object is not an instance of declaring class at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.get(BeanPropertyWriter.java:726) at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:506) at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644) at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)

@Entity
@Table(name = "users")
@JsonAutoDetect
public class Users  implements java.io.Serializable {

  @JsonBackReference
    private List<Event> eventByUser = new ArrayList<Event>(
            0);

    @Id
    @GeneratedValue
    @Column(name = "USER_ID", unique = true)
    public Long getUserId() {
        return userIds;
    }
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "user")
    @Fetch(FetchMode.JOIN)
    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    @JsonIgnore
    public List<Event> getEventByUser() {
        return eventByUser;
    }
}


  @Entity
    @Table(name = "EVENT")
    @Inheritance(strategy=InheritanceType.JOINED)
    public class Event  implements java.io.Serializable {

        private Integer eventId;

        @Id
        @GeneratedValue
        @Column(name = "COOKING_EVENT_ID", unique = true)
        public Integer getEventId() {
            return eventId;
        }
        private Users user;

        @ManyToOne(fetch = FetchType.LAZY)
    @Fetch(FetchMode.SELECT)
    @JsonIgnore
    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    @JoinColumn(name = "ASSIGNED_USER_ID", nullable = false)
    @JsonManagedReference
    public Users getUser() {
        return user;
    }

        public void setEventId(Integer eventId) {
            this.eventId = eventId;
        }



 @Entity
    @Table(name = "COOKING_REQUEST_EVENT") @PrimaryKeyJoinColumn(name="EVENT_ID") 
public class CookingRequestEvent extends Event implements java.io.Serializable {

        //Other Variables along with setters and getters 

        }

I have a Jersey controller as below which returns a List

  @GET
        @Path("/cookingEventsByUser/{userId}")
        @Produces({ MediaType.APPLICATION_JSON})
        public List<CookingEvent>  getEventsById(@PathParam("userId") Long id)
                throws JsonGenerationException, JsonMappingException, IOException {
          List<CookingEvent> events  = new ArrayList<CookingEvent>();
         events =  cookingEventServices.getCookingEventsByUser(id);

        } 

I am using Spring Boot + Jersey + hibernate