This example is demonstrating the use of node uniqueness. Below an imaginary domain graph with Principals that own pets that are descendant to other pets.

descendants1

In order to return which all descendants of Pet0 which have the relation owns to Principal1 (Pet1 and Pet3), the Uniqueness of the traversal needs to be set to NODE_PATH rather than the default NODE_GLOBAL so that nodes can be traversed more that once, and paths that have different nodes but can have some nodes in common (like the start and end node) can be returned.

final Node target = data.get().get( "Principal1" );
TraversalDescription td = Traversal.description().uniqueness(Uniqueness.NODE_PATH ).evaluator( new Evaluator()
{
    @Override
    public Evaluation evaluate( Path path )
    {
        if(path.endNode().equals( target )) {
            return Evaluation.INCLUDE_AND_PRUNE;
        }
        return Evaluation.EXCLUDE_AND_CONTINUE;
    }
} );

Traverser results = td.traverse( start );

This will return the following paths:

(3)--[descendant,0]-->(1)<--[owns,3]--(5)
(3)--[descendant,2]-->(4)<--[owns,5]--(5)