feat: changed JSON return types to optionals

src/main/java/uulm/teamname/marvelous/gamelibrary/json/JSON.java

@@ -7,6 +7,8 @@ import uulm.teamname.marvelous.gamelibrary.config.CharacterConfig;
 import uulm.teamname.marvelous.gamelibrary.messages.BasicMessage;
 import uulm.teamname.marvelous.gamelibrary.messages.server.EventMessage;
 
+import java.util.Optional;
+
 /**
  * Class that contains JSON encoding and decoding. It is initiated with the Character configuration.
  */
@@ -23,29 +25,30 @@ public class JSON {
 
     /** Deserializes an incoming network message into a {@link EventMessage}.
      * @param input The JSON to deserialize
-     * @return The parsed message (as {@link BasicMessage}, so casting is necessary)
+     * @return An {@link Optional} containing the parsed message (as {@link BasicMessage}, so typecasting is necessary)
-     *         or {@code null} if the deserialization failed
+     *         or an empty {@link Optional} if the deserialization failed
      */
-    public BasicMessage parse(String input) {
+    public Optional<BasicMessage> parse(String input) {
         BasicMessage result = null;
         try {
-            return mapper.readValue(input, BasicMessage.class);
+            return Optional.of(mapper.readValue(input, BasicMessage.class));
         } catch (JsonProcessingException e) {
-            // e.printStackTrace();
+            e.printStackTrace();
-            return null;
+            return Optional.empty();
         }
     }
 
     /** Serializes a {@link EventMessage} into a JSON string.
      * @param input The message to serialize
-     * @return The message as JSON or {@code null} if the serialization failed
+     * @return An {@link Optional}<{@link String}> of the message as JSON or
+     *         an empty {@link Optional} if the serialization failed
      */
-    public String stringify(BasicMessage input) {
+    public Optional<String> stringify(BasicMessage input) {
         try {
-            return mapper.writeValueAsString(input);
+            return Optional.of(mapper.writeValueAsString(input));
         } catch (JsonProcessingException e) {
-            // e.printStackTrace();
+            e.printStackTrace();
-            return null;
+            return Optional.empty();
         }
     }
 }