GORM Stale对象异常

Question

将记录插入域对象时，我们收到错误：

Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect) 
Stacktrace follows:
org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect)

我们有一个简单的域名：

User{
    String uid
    String firstName
    String lastName
}

在做的时候：

def user=new User(uid:"TestUser", firstName:"Test", lastName:"User")

我们收到了上述错误。