docs: Event-driven architecture explanation (#2917)

* update readme

* convert to record

event-driven-architecture/src/main/java/com/iluwatar/eda/handler/UserCreatedEventHandler.java

@@ -36,7 +36,7 @@ public class UserCreatedEventHandler implements Handler<UserCreatedEvent> {
 
   @Override
   public void onEvent(UserCreatedEvent event) {
-    LOGGER.info("User '{}' has been Created!", event.getUser().getUsername());
+    LOGGER.info("User '{}' has been Created!", event.getUser().username());
   }
 
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/handler/UserUpdatedEventHandler.java

@@ -36,6 +36,6 @@ public class UserUpdatedEventHandler implements Handler<UserUpdatedEvent> {
 
   @Override
   public void onEvent(UserUpdatedEvent event) {
-    LOGGER.info("User '{}' has been Updated!", event.getUser().getUsername());
+    LOGGER.info("User '{}' has been Updated!", event.getUser().username());
   }
 }

event-driven-architecture/src/main/java/com/iluwatar/eda/model/User.java

@@ -33,9 +33,4 @@ import lombok.RequiredArgsConstructor;
  * This {@link User} class is a basic pojo used to demonstrate user data sent along with the {@link
  * UserCreatedEvent} and {@link UserUpdatedEvent} events.
  */
-@RequiredArgsConstructor
-@Getter
-public class User {
-
-  private final String username;
-}
+public record User(String username) {}