code: public FeatureList selectByAttribute(String key, String value) {
  		if (featindex.containsKey(key)){
  			Map<String,List<FeatureI>> featuresmap = featindex.get(key);
  			if (featuresmap==null) return new FeatureList();
  			List<FeatureI> list = featuresmap.get(value);
  			if (list == null){
  				return new FeatureList();
  			}
  			return  new FeatureList(list);
  		}
  		FeatureList list = new FeatureList();
  		for (FeatureI f : this) {
  			if (f.hasAttribute(key, value)) {
  				list.add(f);
  			}
  		}
  		return list;
  	}
docs: Create a list of all features that include the specified attribute key/value pair.
  This method now properly supports adding the index before or after adding the features.
  Adding features, then then index, then more features is still not supported.
  
  @param key The key to consider.
  @param value The value to consider.
  @return A list of features that include the key/value pair.