The PersistencyHandler can be used to get writeable access to master entities. It is only available for plugins running in the novomind iAGENT routing process.
The Modifier is a staging area where you edit the master entity instance and complete by calling the
Every Master Entity has it's own specific
<MasterEntity>Modifier containing setters for the changable fields. The specific modifiers also support validation of these fields, see for example TenantModifier.