Why Propagation.REQUIRES_NEW on persist()

[weston.pace]

Using Spring Roo 1.1.1 I created a new project and an entity. The commands entered were...

project --topLevelPackage org.sotest.sscce --projectName Test2 --java 6
persistence setup --database GOOGLE_APP_ENGINE --provider DATANUCLEUS
entity --class ~.data.account

I noticed that the persist() method in Account_Roo_Entity.aj is...

    
    @Transactional(propagation = Propagation.REQUIRES_NEW)
    public void Account.persist() {
        if (this.entityManager == null) this.entityManager = entityManager();
        this.entityManager.persist(this);
    }

Why does the persist method have Propagation.REQUIRES_NEW instead of the default propogation?