public Object[] nearestNeighbour( ItemDistance itemDist ) {
        BoundablePair bp = new BoundablePair(this.getRoot(), this.getRoot(), itemDist);
        return nearestNeighbour(bp);
    }
public Object [ ] nearestNeighbour ( ItemDistance itemDist ) { BoundablePair bp = new BoundablePair ( this . getRoot ( ) , this . getRoot ( ) , itemDist ) ; return nearestNeighbour ( bp ) ; }
Finds the two nearest items in the tree,
using {@link org.locationtech.jts.index.strtree.ItemDistance} as the distance metric.
A Branch-and-Bound tree traversal algorithm is used
to provide an efficient search.

@param itemDist a distance metric applicable to the items in this tree
@return the pair of the nearest items