¿How can I insert in a custom subform usign API V2 and Java SDK?

¿How can I insert in a custom subform usign API V2 and Java SDK?

I´m using Java SDK with API V2. I have a custom module and a subform in this module. I can create a new record in the module, but I can´t create a record in the subform. I'm trying to do something like this:

public void createRecords() throws Exception {
      ZCRMRecord record=ZCRMRecord.getInstance("Facturas_WO",null); 
      record.setFieldValue("Name","16076");
      record.setFieldValue("NIT", 9999);
      record.setFieldValue("Subformulario_1.Item"+1, "eeee!!!");//trying to insert in subform
      APIResponse response = record.create();
      response.getData();
}

Thanks alot for your help.