Update to Minecraft 1.15

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

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

@@ -0,0 +1,12 @@
+package org.bukkit.inventory;
+
+import org.bukkit.Keyed;
+
+/**
+ * Represents a complex recipe which has imperative server-defined behavior, eg
+ * armor dyeing.
+ *
+ * Note: Since a complex recipe has dynamic outputs, {@link #getResult()} will
+ * sometimes return an AIR ItemStack.
+ */
+public interface ComplexRecipe extends Recipe, Keyed {}