code: public String getValue(String property, String language) {
          Multimap<Optional<String>, String> values = properties.get(property);
  
          if (values == null) {
              return null;
          }
  
          Iterator<String> it = values.get(Optional.of(language)).iterator();
          return it.hasNext() ? it.next() : null;
      }
docs: Get a literal value for a property and language passed by parameters
  
  @param property Property URI
  @param language Language code
  @return