[ValidationException: HV000041: Call to TraversableResolver.isReachable() threw an exception.]

Play Framework todolist 예제를 따라하다가 발생한 에러

검색해보면 setter/getter를 추가해라는 답변도 있는데, 콘솔 에러를 보면

! @6f4fl4mol - Internal server error, for (POST) [/tasks] ->

play.api.Application$$anon$1: Execution exception[[ValidationException: HV000041: Call to TraversableResolver.isReachable() threw an exception.]]
        at play.api.Application$class.handleError(Application.scala:289) ~[play_2.10.jar:2.1.2]
    ...
        at org.hibernate.validator.internal.engine.ValidatorImpl.validate(ValidatorImpl.java:133) ~[hibernate-validator.jar:4.3.0.Final]
Caused by: java.lang.RuntimeException: No @javax.persistence.Id field found in class [class models.Task]
        at play.db.ebean.Model._idAccessors(Model.java:54) ~[play-java-ebean_2.10.jar:2.1.2]
        at play.db.ebean.Model._getId(Model.java:67) ~[play-java-ebean_2.10.jar:2.1.2]
        at play.db.ebean.Model.hashCode(Model.java:208) ~[play-java-ebean_2.10.jar:2.1.2]
        at org.hibernate.validator.internal.engine.resolver.SingleThreadCachedTraversableResolver$TraversableHolder.buildHashCode(SingleThreadCachedTraversableResolver.java:153) ~[hibernate-validator.jar:4.3.0.Final]
        at org.hibernate.validator.internal.engine.resolver.SingleThreadCachedTraversableResolver$TraversableHolder.<init>(SingleThreadCachedTraversableResolver.java:114) ~[hibernate-validator.jar:4.3.0.Final]
        at org.hibernate.validator.internal.engine.resolver.SingleThreadCachedTraversableResolver$TraversableHolder.<init>(SingleThreadCachedTraversableResolver.java:96) ~[hibernate-validator.jar:4.3.0.Final]

1.X 문서에서는 Play Model 클래스에서 @Id를 제공한다고 해서, @Id를 넣지 않아서 발생했다.