added ex K

src/exercises/ex_k/Package.java

@@ -0,0 +1,15 @@
+package exercises.ex_k;
+
+public class Package {
+    private Customer sender;
+
+    public Package(Customer sender) {
+        this.sender = sender;
+    }
+    @Override
+    public String toString() {
+        return "Package{" +
+            "sender=" + sender.getName() +
+            '}';
+    }
+}