Associations Grails/Gorm - grails

Question

I have the the domain classes Rep and Bill. Bill has two fields of the type Rep called sponsor and cosponsor. I have set up the association in Bill as static hasMany = [sponsor: Rep, cosponsor: Rep]. When ever I try to save I get NULL not allowed for column "BILL_SPONSOR_ID"; SQL statement: insert into bill_rep (bill_cosponsor_id, rep_id) values (?, ?) [23502-193]. I understand that for some reason the the correct ids are not getting inserted. I have tried set both sponsor and cosponsor to nullable but I have not been able to get around it. Any idea as to what I am doing wrong?
class Bill {
String billPre
String number
String billName
Integer dateIntro
String summary
static hasMany = [cosponsor: Rep, sponsor: Rep, committee: Committee]
static constraints = {
cosponsor nullable: true
sponsor nullable: true
}
String toString() {
billName
}
}
class Rep {
String name
String party
String congress
Integer district
String state
String repEmail
String street
String phone
Integer congStart
Integer congEnd
Integer congNumStart
Integer congNumEnd
static constraints = {
name()
party()
district()
congress inList: ["House", "Senate"]
state inList: ['Alabama', 'Alaska', 'Arizona', 'Arkansas', 'California', 'Colorado', 'Connecticut', 'Delaware', 'Florida', 'Georgia', 'Hawaii', 'Idaho', 'Illinois', 'Indiana', 'Iowa', 'Kansas', 'Kentucky', 'Louisiana', 'Maine', 'Maryland', 'Massachusetts', 'Michigan', 'Minnesota', 'Mississippi', 'Missouri', 'Montana', 'Nebraska', 'Nevada', 'New Hampshire', 'New Jersey', 'New Mexico', 'New York', 'North Carolina', 'North Dakota', 'Ohio', 'Oklahoma', 'Oregon', 'Pennsylvania', 'Rhode Island', 'South Carolina', 'South Dakota', 'Tennessee', 'Texas', 'Utah', 'Vermont', 'Virginia', 'Washington', 'West Virginia', 'Wisconsin', 'Wyoming']
party inList: ["Republican", "Democrat"]
repEmail email: true
street()
phone()
congStart()
congEnd()
congNumStart()
congNumEnd()
}
String toString() {
name
}
}