update

src/main/java/PingPong/CollisionChecker.java

@@ -0,0 +1,7 @@
+package PingPong;
+
+public class CollisionChecker {
+    public Boolean didTouchTopOrBottomEdge(Integer ballYCoordinate, Integer maxHeight) {
+        return ballYCoordinate <= 0 || ballYCoordinate >= maxHeight;
+    }
+}