[Avaje Inject Module] Fix property plugin

Author: SentryMan

modules/jooby-avaje-inject/src/main/java/io/jooby/avaje/inject/JoobyPropertyPlugin.java

@@ -22,8 +22,8 @@ public JoobyPropertyPlugin(Config config) {
   @Override
   public Optional<String> get(String property) {
     return config.hasPath(property)
-        ? Optional.empty()
-        : Optional.ofNullable(config.getString(property));
+        ? Optional.of(config.getString(property))
+        : Optional.empty();
   }
 
   @Override