feat: added notification pattern (#2629)

Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>

notification/src/main/java/com/iluwatar/ServerCommand.java

@@ -0,0 +1,21 @@
+package com.iluwatar;
+
+import lombok.AllArgsConstructor;
+
+/**
+ * Stores the dto and access the notification within it.
+ * Acting as a layer supertype in this instance for the domain layer.
+ */
+@AllArgsConstructor
+public class ServerCommand {
+  protected DataTransferObject data;
+
+  /**
+   * Basic getter to extract information from our data.
+   *
+   * @return the notification stored within the data
+   */
+  public Notification getNotification() {
+    return data.getNotification();
+  }
+}