Minor API changed to ensure backward compatibility

TULIP/src/lu/list/itis/dkd/tui/feature/cluster/Cluster.java

@@ -118,7 +118,7 @@ public class Cluster<T extends Positionable> {
 
     // ---------------------------------------------------------------------------
 
-    public List<Point> getPositions() {
+    public Collection<Point> getPositions() {
         List<Point> positions = new ArrayList<>();
         this.points.forEach(point -> positions.add(point.getPosition()));
         return positions;

TULIP/src/lu/list/itis/dkd/tui/utility/ShapeUtils.java

@@ -41,6 +41,7 @@ import java.awt.geom.Rectangle2D;
 import java.awt.geom.RoundRectangle2D;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -1193,7 +1194,7 @@ public class ShapeUtils {
      */
     // ---------------------------------------------------------------------------
 
-    public static Path2D alphaShape(List<Point> pointCloud, double alpha, double smoothing, int iterations) {
+    public static Path2D alphaShape(Collection<Point> pointCloud, double alpha, double smoothing, int iterations) {
         List<TriangulationPoint> polyPoints = new ArrayList<>(pointCloud.size());
         for (Point point : pointCloud) {
             polyPoints.add(new TPoint(Math.floor(point.getX()), Math.floor(point.getY())));