question: public double fullPathDistance ( final DistanceStyle distanceStyle ) { synchronized ( fullDistanceCache ) { Double dist = fullDistanceCache . get ( distanceStyle ) ; if ( dist == null ) { dist = new Double ( distanceStyle . computeDistance ( start , end . x , end . y , end . z ) ) ; fullDistanceCache . put ( distanceStyle , dist ) ; } return dist . doubleValue ( ) ; } }
target:  Compute the full distance along this path segment.