public string CreateFeature(string landlordReference, string submittedPropertyReference, Feature feature) { Check.If(landlordReference).IsNotNullOrEmpty(); Check.If(submittedPropertyReference).IsNotNullOrEmpty(); Check.If(feature).IsNotNull(); var result = _featureRepository.CreateFeature(landlordReference, submittedPropertyReference, feature.CreateReference(_referenceGenerator)); return result ? feature.FeatureReference : null; }