code: public void addUniqueFields(Set<FieldSet> uniqueFieldSets) {
  		if (this.uniqueFields == null) {
  			this.uniqueFields = new HashSet<FieldSet>();
  		}
  		this.uniqueFields.addAll(uniqueFieldSets);
  	}
docs: Adds multiple FieldSets to be unique
  
  @param uniqueFieldSets A set of unique FieldSet