Hibernate : self reference FK in same table as well as different table

I have 2 tables as below

historyQuestions
=====================
开发者_如何学Goquestion_id bigint(2) PK
question_master_id bigint(2) fk references question_master(question_id)
parent_question_id bigint(2) fk references historyQuestions(question_id)
parent_answer_id bigint(2) fk references historyAnswers(answer_id)

historyAnswers
=====================
answer_id bigint(2) pk
question_id bigint(2) fk references historyQuestions(question_id)
answer_master_id bigint(2) fk references answer_master(answer_id)

Now I want to newly insert records using hibernate

session.save(entityObj)

but it gives me

exception org.hibernate.StaleStateException

Any help would be appriciate..

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COPIED DIRECTLY FROM HIBERNATE JAVADOC, please, google your exception and do some research first.

Thrown when a version number or timestamp check failed, indicating that the Session contained stale data (when using long transactions with versioning). Also occurs if we try delete or update a row that does not exist.

Note that this exception often indicates that the user failed to specify the correct unsaved-value strategy for a class!