Clarify MerchantInventory#getSelectedRecipe.

By: blablubbabc <lukas@wirsindwir.de>

paper-api/src/main/java/org/bukkit/inventory/MerchantInventory.java

@@ -16,9 +16,15 @@ public interface MerchantInventory extends Inventory {
     int getSelectedRecipeIndex();
 
     /**
-     * Get the currently selected recipe.
+     * Get the currently active recipe.
+     * <p>
+     * This will be <code>null</code> if the items provided by the player do
+     * not match the ingredients of the selected recipe. This does not
+     * necessarily match the recipe selected by the player: If the player has
+     * selected the first recipe, the merchant will search all of its offers
+     * for a matching recipe to activate.
      *
-     * @return the currently selected recipe
+     * @return the currently active recipe
      */
     MerchantRecipe getSelectedRecipe();
 }