code: @Override
  	public <T extends Serializable, S extends Individual<T,S>> T firstIndividual(final Class<? extends S> clazz) {
  		Property property=getProperty();
  		if(property==null) {
  			return null;
  		}
  		IndividualExtractor<T,S> extractor=IndividualExtractor.newInstance(clazz);
  		for(Value value:property) {
  			value.accept(extractor);
  			if(extractor.isAvailable()) {
  				return extractor.getValue().id();
  			}
  		}
  		return null;
  	}
docs: {@inheritDoc}