From 1114d726cddc73b21424951b137811b8228d3065 Mon Sep 17 00:00:00 2001
From: CraftBukkit/Spigot <noreply+git-craftbukkit@papermc.io>
Date: Sat, 24 Nov 2018 17:52:29 +1100
Subject: [PATCH] SPIGOT-4500: callSyncMethod broken

By: md_5 <git@md-5.net>
---
 .../java/org/bukkit/craftbukkit/scheduler/CraftScheduler.java   | 2 +-
 .../main/java/org/bukkit/craftbukkit/scheduler/CraftTask.java   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftScheduler.java b/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftScheduler.java
index b5c22e209f..557f72d621 100644
--- a/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftScheduler.java
+++ b/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftScheduler.java
@@ -437,7 +437,7 @@ public class CraftScheduler implements BukkitScheduler {
     private static void validate(final Plugin plugin, final Object task) {
         Validate.notNull(plugin, "Plugin cannot be null");
         Validate.notNull(task, "Task cannot be null");
-        Validate.isTrue(task instanceof Runnable || task instanceof Consumer, "Task must be Runnable or Consumer");
+        Validate.isTrue(task instanceof Runnable || task instanceof Consumer || task instanceof Callable, "Task must be Runnable, Consumer, or Callable");
         if (!plugin.isEnabled()) {
             throw new IllegalPluginAccessException("Plugin attempted to register task while disabled");
         }
diff --git a/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftTask.java b/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftTask.java
index 15c62552e7..a85fbbb693 100644
--- a/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftTask.java
+++ b/paper-server/src/main/java/org/bukkit/craftbukkit/scheduler/CraftTask.java
@@ -46,7 +46,7 @@ class CraftTask implements BukkitTask, Runnable {
             this.cTask = (Consumer<BukkitTask>) task;
             this.rTask = null;
         } else if (task == null) {
-            // Head task
+            // Head or Future task
             this.rTask = null;
             this.cTask = null;
         } else {