GORM: What is reference:true in Grails domain class mapping block? -

public class address {     static mapwith = "mongo"      region region;     zone zone;      static mapping = {         id generator: 'identity'         region reference:true         zone reference:true     } } 

i'm interested in knowing reference:true does.

in experience, leaving off gives same result except there's no dbref in actual mongo document.

it looks reference controlls how documents linked.

when true, related documents referenced db-refs, if false, gorm inserts simple id, aka manual references in mongo