Fix Optional null issue - Fixes #3155

Also check class loader cache before locking to speed up cached hits to avoid the lock

wasn't gonna make a unique build just for that but can lump it in here.

Spigot-API-Patches/0196-Make-JavaPluginLoader-thread-safe.patch

@@ -1,11 +1,11 @@
-From eae57c232e30ee963d3ca6f69a5dc10179be5858 Mon Sep 17 00:00:00 2001
+From 8ee6c03819b3128a206f5a5a73002bd719baf25b Mon Sep 17 00:00:00 2001
 From: Trigary <trigary0@gmail.com>
 Date: Wed, 15 Apr 2020 01:24:55 -0400
 Subject: [PATCH] Make JavaPluginLoader thread-safe
 
 
 diff --git a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
-index 8ff228ce..c0884f27 100644
+index 8ff228ce..ba2c5c6e 100644
 --- a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
 +++ b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
 @@ -52,6 +52,8 @@ public final class JavaPluginLoader implements PluginLoader {
@@ -17,22 +17,27 @@ index 8ff228ce..c0884f27 100644
      private final List<PluginClassLoader> loaders = new CopyOnWriteArrayList<PluginClassLoader>();
  
      /**
-@@ -191,6 +193,14 @@ public final class JavaPluginLoader implements PluginLoader {
+@@ -191,7 +193,19 @@ public final class JavaPluginLoader implements PluginLoader {
  
      @Nullable
      Class<?> getClassByName(final String name) {
 +        // Paper start - make MT safe
+         Class<?> cachedClass = classes.get(name);
++        if (cachedClass != null) {
++            return cachedClass;
++        }
 +        java.util.concurrent.locks.ReentrantReadWriteLock lock;
 +        synchronized (classLoadLock) {
 +            lock = classLoadLock.computeIfAbsent(name, (x) -> new java.util.concurrent.locks.ReentrantReadWriteLock());
 +            classLoadLockCount.compute(name, (x, prev) -> prev != null ? prev + 1 : 1);
 +        }
 +        lock.writeLock().lock();try {
++        cachedClass = classes.get(name);
 +        // Paper end
-         Class<?> cachedClass = classes.get(name);
  
          if (cachedClass != null) {
-@@ -205,6 +215,19 @@ public final class JavaPluginLoader implements PluginLoader {
+             return cachedClass;
+@@ -205,6 +219,19 @@ public final class JavaPluginLoader implements PluginLoader {
                  }
              }
          }

Spigot-Server-Patches/0472-Reduce-Either-Optional-allocation.patch

@@ -1,4 +1,4 @@
-From e5ba87668be36b649b80633170a33e7ad3fae019 Mon Sep 17 00:00:00 2001
+From f05a44606eb3f3467c092da8ade51d8de1220561 Mon Sep 17 00:00:00 2001
 From: Spottedleaf <spottedleaf@spottedleaf.dev>
 Date: Mon, 6 Apr 2020 18:35:09 -0700
 Subject: [PATCH] Reduce Either Optional allocation
@@ -7,7 +7,7 @@ In order to get chunk values, we shouldn't need to create
 an optional each time.
 
 diff --git a/src/main/java/com/mojang/datafixers/util/Either.java b/src/main/java/com/mojang/datafixers/util/Either.java
-index a90adac7b..efae74b71 100644
+index a90adac7b..4bb621d57 100644
 --- a/src/main/java/com/mojang/datafixers/util/Either.java
 +++ b/src/main/java/com/mojang/datafixers/util/Either.java
 @@ -22,10 +22,10 @@ public abstract class Either<L, R> implements App<Either.Mu<R>, L> {
@@ -19,7 +19,7 @@ index a90adac7b..efae74b71 100644
  
          public Left(final L value) {
 -            this.value = value;
-+            this.value = value; this.valueOptional = Optional.of(value);  // Paper - reduce the optional allocation...
++            this.value = value; this.valueOptional = value != null ? Optional.of(value) : Optional.empty();  // Paper - reduce the optional allocation...
          }
  
          @Override
@@ -41,7 +41,7 @@ index a90adac7b..efae74b71 100644
  
          public Right(final R value) {
 -            this.value = value;
-+            this.value = value; this.valueOptional = Optional.of(value); // Paper - reduce the optional allocation...
++            this.value = value; this.valueOptional = value != null ? Optional.of(value) : Optional.empty(); // Paper - reduce the optional allocation...
          }
  
          @Override