code: public void addUniqueField(FieldSet uniqueFieldSet) {
  		if (this.uniqueFields == null) {
  			this.uniqueFields = new HashSet<FieldSet>();
  		}
  		this.uniqueFields.add(uniqueFieldSet);
  	}
docs: Adds a FieldSet to be unique
  
  @param uniqueFieldSet The unique FieldSet