added ex U

src/exercises/ex_u/FamilyMember.java

@@ -0,0 +1,22 @@
+package exercises.ex_u;
+
+import java.util.concurrent.CountDownLatch;
+
+public class FamilyMember implements Runnable {
+    private final String name;
+    private final Vehicle vehicle;
+    private final CountDownLatch countDownLatch;
+
+    public FamilyMember(String name, Vehicle vehicle, CountDownLatch countDownLatch) {
+        this.name = name;
+        this.vehicle = vehicle;
+        this.countDownLatch = countDownLatch;
+    }
+
+    @Override
+    public void run() {
+        vehicle.addSuitcase(name + "'s suitcase");
+        System.out.println(name + " has loaded their suitcase");
+        countDownLatch.countDown();
+    }
+}