refactor: change event deserialization return type to optional

Author: AndreaGiulianelli

src/env/application/presenter/event/serialization/EventDeserializer.java

@@ -10,6 +10,8 @@
 
 import application.presenter.event.model.Event;
 
+import java.util.Optional;
+
 /**
  * Interface that models an event deserializer.
  */
@@ -18,7 +20,7 @@ public interface EventDeserializer {
      * Deserialize an event from string.
      * @param eventKey the key of the event.
      * @param event the event in string format.
-     * @return the deserialized event.
+     * @return the deserialized event as an optional.
      */
-    Event<?> fromString(String eventKey, String event);
+    Optional<Event<?>> fromString(String eventKey, String event);
 }

src/env/application/presenter/event/serialization/EventDeserializerImpl.java

@@ -22,6 +22,7 @@
 import java.lang.reflect.Type;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
 
 /**
  * Implementation of the {@link EventDeserializer} interface that allows an event to be
@@ -45,10 +46,9 @@ public EventDeserializerImpl() {
     }
 
     @Override
-    public final Event<?> fromString(final String eventKey, final String event) {
-        if (!this.typeMap.containsKey(eventKey)) {
-            throw new IllegalArgumentException("Event not supported");
-        }
-        return new Gson().fromJson(event, this.typeMap.get(eventKey));
+    public final Optional<Event<?>> fromString(final String eventKey, final String event) {
+        return Optional.of(eventKey)
+                .filter(this.typeMap::containsKey)
+                .map(key -> new Gson().fromJson(event, this.typeMap.get(key)));
     }
 }

src/env/infrastructure/events/KafkaClient.java

@@ -72,7 +72,7 @@ public void poll(final Consumer<Event<?>> eventConsumer) {
             this.kafkaConsumer.poll(Duration.ofMillis(POLLING_TIME)).forEach(event -> {
                 // log the event
                 Logger.getLogger(KafkaClient.class.getName()).fine(event.toString());
-                eventConsumer.accept(this.eventDeserializer.fromString(event.key(), event.value()));
+                this.eventDeserializer.fromString(event.key(), event.value()).ifPresent(eventConsumer);
             });
         }
     }