By default the direction of links is taken into account when looking for paths or cycles. In that case the direction of a path is considered to be the direction defined by the outgoing links of nodes. Use the second constructor override to specify that link direction should be ignored when looking for paths.
A path-finder object caches graph information between method calls in order to achieve better performance when path and cycle -finding methods are called on the same diagram more than once. However if the diagram structure changes, you must create a new PathFinder instance in order to use the new structure of the diagram graph.