code: public DoubleProperty lengthProperty() {
  		if (this.length == null) {
  			this.length = new ReadOnlyDoubleWrapper();
  			this.length.bind(Bindings.createDoubleBinding(() ->
  				Path3afp.computeLength(getPathIterator()),
  				innerTypesProperty(), innerCoordinatesProperty()));
  		}
  		return this.length;
  	}
docs: Replies the path length property.
  
  @return the length property.