fix: use own methods in JSON constructor and add javadoc

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

@@ -94,10 +94,7 @@ public class JSON {
     private final ObjectMapper mapper = new ObjectMapper();
 
     public JSON (CharacterConfig config) {
-        // add the config to the mappers InjectableValues, where it is later accessed by the EntityDeserializer
-        this.mapper.setInjectableValues(new InjectableValues
-                .Std()
-                .addValue("CharacterConfig", config));
+        setCharacterConfig(config);
     }
 
     /** Deserializes an incoming network message into a {@link EventMessage}.
@@ -132,6 +129,9 @@ public class JSON {
         }
     }
 
+    /**
+     * Sets the {@link CharacterConfig} to be used during deserialization of Entities.
+     */
     public void setCharacterConfig(CharacterConfig config) {
         this.mapper.setInjectableValues(new InjectableValues
                 .Std()