Add warning to getOfflinePlayers (#6365)

patches/api/0053-Fix-upstream-javadocs.patch

@@ -0,0 +1,72 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Zach Brown <zach.brown@destroystokyo.com>
+Date: Sat, 10 Jun 2017 16:59:40 -0500
+Subject: [PATCH] Fix upstream javadocs
+
+Upstream still refuses to use Java 8 with the API so they are likely unaware these are even issues.
+
+diff --git a/src/main/java/org/bukkit/Bukkit.java b/src/main/java/org/bukkit/Bukkit.java
+index 02045103fc776a149cd05a779461acb6164b656f..03f5d90d58617d463cb15e0b1d5b7bd76d8f4b21 100644
+--- a/src/main/java/org/bukkit/Bukkit.java
++++ b/src/main/java/org/bukkit/Bukkit.java
+@@ -1123,6 +1123,8 @@ public final class Bukkit {
+ 
+     /**
+      * Gets every player that has ever played on this server.
++     * <p>
++     * <b>This method can be expensive as it loads all the player data files from the disk.</b>
+      *
+      * @return an array containing all previous players
+      */
+diff --git a/src/main/java/org/bukkit/Server.java b/src/main/java/org/bukkit/Server.java
+index 1d13a4c289e6a764b3b080455a86e17a5e60929e..294b6092b438ad3d09bf3ad28d08ffdfdda4ac5c 100644
+--- a/src/main/java/org/bukkit/Server.java
++++ b/src/main/java/org/bukkit/Server.java
+@@ -945,6 +945,8 @@ public interface Server extends PluginMessageRecipient, net.kyori.adventure.audi
+ 
+     /**
+      * Gets every player that has ever played on this server.
++     * <p>
++     * <b>This method can be expensive as it loads all the player data files from the disk.</b>
+      *
+      * @return an array containing all previous players
+      */
+diff --git a/src/main/java/org/bukkit/entity/Player.java b/src/main/java/org/bukkit/entity/Player.java
+index 9d5c5b5f7d7ae4f0278410833d9d385242872498..2301a5c6ada86b63b1c0207a6d89b0da4c167bbb 100644
+--- a/src/main/java/org/bukkit/entity/Player.java
++++ b/src/main/java/org/bukkit/entity/Player.java
+@@ -730,7 +730,7 @@ public interface Player extends HumanEntity, Conversable, OfflinePlayer, PluginM
+      *
+      * Use supplied alternative character to the section symbol to represent legacy color codes.
+      *
+-     * @param alternateChar Alternate symbol such as '&'
++     * @param alternateChar Alternate symbol such as '&amp;'
+      * @param message The message to send
+      * @deprecated use {@link #sendActionBar(Component)}
+      */
+diff --git a/src/main/java/org/bukkit/event/player/PlayerMoveEvent.java b/src/main/java/org/bukkit/event/player/PlayerMoveEvent.java
+index 1b2267f4e8ebded198773ec80e2bff2c861c7084..1a58734d919fae247eeb85dd785fd59990856505 100644
+--- a/src/main/java/org/bukkit/event/player/PlayerMoveEvent.java
++++ b/src/main/java/org/bukkit/event/player/PlayerMoveEvent.java
+@@ -78,7 +78,7 @@ public class PlayerMoveEvent extends PlayerEvent implements Cancellable {
+      *
+      * @return Location the player moved to
+      */
+-    @Nullable
++    @NotNull // Paper
+     public Location getTo() {
+         return to;
+     }
+diff --git a/src/main/java/org/bukkit/inventory/PlayerInventory.java b/src/main/java/org/bukkit/inventory/PlayerInventory.java
+index 99d900b2394b6c210ccf845768dae72864f32270..515587a958041e94f03c48ae87812abc39e1791c 100644
+--- a/src/main/java/org/bukkit/inventory/PlayerInventory.java
++++ b/src/main/java/org/bukkit/inventory/PlayerInventory.java
+@@ -106,7 +106,7 @@ public interface PlayerInventory extends Inventory {
+      *
+      * @return the ItemStack in the given slot
+      */
+-    @NotNull
++    @Nullable
+     public ItemStack getItem(@NotNull EquipmentSlot slot);
+ 
+     /**