I have two domains :

class CodeSet { 

  String id
  String owner
  String comments
  String geneRLF
  String systemAPF

  static hasMany = [cartridges:Cartridge]

    static constraints = {
      id(unique:true,blank:false)
    }

    static mapping = {
      table 'code_set'
      version false
      columns {
         id column:'code_set_id', generator: 'assigned'
         owner column:'owner'
         comments column:'comments'
         geneRLF column:'gene_rlf'
         systemAPF column:'system_apf'
      }
  }

and :

class Cartridge {

  String id
  String code_set_id
  Date runDate

  static belongsTo = CodeSet

    static constraints = {
      id(unique:true,blank:false)
    }

      static mapping = {
      table 'cartridge'
      version false
      columns {
         id column:'cartridge_id', generator: 'assigned'
         code_set_id column:'code_set_id'
         runDate column:'run_date'
      }
  }

Actually, with those models, I get tables :
- code_set,
- cartridge,
- and table : code_set_cartridge (two fields : code_set_cartridges_id, cartridge_id)

I would like to not have code_set_cartridge table, but keep relationship :
code_set --> 1:n --> cartridge

In other words, how can I keep association between code_set and cartridge without intermediate table ? (using code_set_id as primary key in code_set and code_set_id as foreign key in cartridge).

Mapping with GORM can be done without intermediate table?