feat: added notification pattern (#2629)

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

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

@@ -0,0 +1,26 @@
+package com.iluwatar;
+
+import java.util.ArrayList;
+import java.util.List;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+/**
+ * The notification. Used for storing errors and any other methods
+ * that may be necessary for when we send information back to the
+ * presentation layer.
+ */
+@Getter
+@NoArgsConstructor
+public class Notification {
+
+  private final List<NotificationError> errors = new ArrayList<>();
+
+  public boolean hasErrors() {
+    return !this.errors.isEmpty();
+  }
+
+  public void addError(NotificationError error) {
+    this.errors.add(error);
+  }
+}