Updated Upstream (Paper)

Upstream has released updates that appear to apply and compile correctly

patches/api/0001-Airplane-API-Changes.patch

@@ -0,0 +1,58 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Paul Sauve <paul@technove.co>
+Date: Sat, 19 Dec 2020 19:06:37 -0600
+Subject: [PATCH] Airplane API Changes
+
+Copyright (C) 2020 Technove LLC
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+diff --git a/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java b/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java
+index 1ab107d5bb20b9a12fc8843513bd9a3ada50c0a3..70aa79c0bfde6aea8031eeb69124344ab3af5c27 100644
+--- a/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java
++++ b/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java
+@@ -46,6 +46,8 @@ public final class PluginClassLoader extends URLClassLoader { // Spigot
+     private final Set<String> seenIllegalAccess = Collections.newSetFromMap(new ConcurrentHashMap<>());
+     private java.util.logging.Logger logger; // Paper - add field
+ 
++    private boolean closed = false; // Airplane
++
+     static {
+         ClassLoader.registerAsParallelCapable();
+     }
+@@ -146,6 +148,7 @@ public final class PluginClassLoader extends URLClassLoader { // Spigot
+         throw new ClassNotFoundException(name);
+     }
+ 
++    public boolean _airplane_hasClass(@NotNull String name) { return this.classes.containsKey(name); } // Airplane
+     @Override
+     protected Class<?> findClass(String name) throws ClassNotFoundException {
+         if (name.startsWith("org.bukkit.") || name.startsWith("net.minecraft.")) {
+@@ -153,7 +156,7 @@ public final class PluginClassLoader extends URLClassLoader { // Spigot
+         }
+         Class<?> result = classes.get(name);
+ 
+-        if (result == null) {
++        if (result == null && !this.closed) { // Airplane
+             String path = name.replace('.', '/').concat(".class");
+             JarEntry entry = jar.getJarEntry(path);
+ 
+@@ -208,6 +211,7 @@ public final class PluginClassLoader extends URLClassLoader { // Spigot
+         try {
+             super.close();
+         } finally {
++            this.closed = true; // Airplane
+             jar.close();
+         }
+     }