Add Override annotations where appropriate

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/configuration/Configuration.java

@@ -22,6 +22,7 @@ public interface Configuration extends ConfigurationSection {
      * @param value Value to set the default to.
      * @throws IllegalArgumentException Thrown if path is null.
      */
+    @Override
     public void addDefault(@NotNull String path, @Nullable Object value);
 
     /**