code: public Object getAttributeValue(FeatureDescriptor feature,
                                      String attributeName) {
  
          if (feature == null || attributeName == null) {
              return null;
          }
  
          return feature.getValue(attributeName);
      }
docs: Retrieves the value of the named FeatureDescriptor attribute.
  
  @return The value of the attribute. May be null if the attribute
  is unknown.