Add new overload to PersistentDataContainer#has (#7278)

Co-authored-by: u9g <winworkswow@gmail.com>
Co-authored-by: Josh Roy <10731363+JRoy@users.noreply.github.com>

patches/api/Add-new-overload-to-PersistentDataContainer-has.patch

@@ -0,0 +1,30 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: u9g <winworkswow@gmail.com>
+Date: Mon, 3 Jan 2022 23:27:21 -0500
+Subject: [PATCH] Add new overload to PersistentDataContainer#has
+
+Adds the new overload: PersistentDataContainer#has(NamespacedKey key)
+
+diff --git a/src/main/java/org/bukkit/persistence/PersistentDataContainer.java b/src/main/java/org/bukkit/persistence/PersistentDataContainer.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/persistence/PersistentDataContainer.java
++++ b/src/main/java/org/bukkit/persistence/PersistentDataContainer.java
+@@ -0,0 +0,0 @@ public interface PersistentDataContainer {
+      */
+     @NotNull
+     PersistentDataAdapterContext getAdapterContext();
++
++    // Paper start
++    /**
++     * Returns if the persistent metadata provider has metadata registered
++     * matching the provided key.
++     * 
++     * @param key the key for which existence should be checked.
++     * 
++     * @return whether the key exists
++     * 
++     * @throws NullPointerException if the key to look up is null
++     */
++    boolean has(@NotNull NamespacedKey key);
++    // Paper end
+ }