public void makeImmutable(){
  if (isMutable) {
    if (audiences != null) {
      audiences=Collections.unmodifiableList(audiences);
    }
    isMutable=false;
  }
}

public void makeImmutable ( ) { if ( isMutable ) { if ( audiences != null ) { audiences = Collections . unmodifiableList ( audiences ) ; } isMutable = false ; } }
makes the object immutable
