关于jbpmcontext.close报错问题

jbpmcontext.close()的时候调用flush报错。
an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session)[MESSAGE]

org.hibernate.AssertionFailure: collection [org.jbpm.file.def.FileDefinition.processFiles] was not processed by flush()

然后给session设置了session.setFlushMode(FlushMode.ALWAYS);
结果还是同样的错，发现是在调用
/* insert collection
        row org.jbpm.bytes.ByteArray.byteBlocks */ insert
        into
            JBPM_BYTEBLOCK
            (PROCESSFILE_, INDEX_, BYTES_)
        values
            (?, ?, ?)[MESSAGE]

/* delete org.jbpm.bytes.ByteArray */ delete
        from
            JBPM_BYTEARRAY
        where
            ID_=?[MESSAGE]

以后报错的，debug的时候没有报错信息。但是release的时候报错了。流程报错也不是百分百出现。。。