Guard the Entity.SHARED_RANDOM from seed changes

I don't clearly see any, but as a protection for future changes.

Spigot-Server-Patches/Cap-Entity-Collisions.patch

@@ -27,7 +27,7 @@ index 5f06d4e5e..29b4bdb47 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 20324deeb..b4233df5f 100644
+index 92b2bcb86..5a4de30fe 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Don-t-allow-entities-to-ride-themselves-572.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Don't allow entities to ride themselves - #572
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index b6711dcfa..e7f63c927 100644
+index 6d1e61e23..92b2bcb86 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Don-t-let-fishinghooks-use-portals.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Don't let fishinghooks use portals
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index c675a6e16..f71528b5f 100644
+index 0950c315f..d79844a98 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Don-t-teleport-dead-entities.patch

@@ -7,7 +7,7 @@ Had some issue with this in past, and this is the vanilla logic.
 Potentially an old CB change that's no longer needed.
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index eb07d4233..e2202ed0c 100644
+index daf97bce3..87b82f908 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Entity-Tracking-Improvements.patch

@@ -7,7 +7,7 @@ If any part of a Vehicle/Passenger relationship is visible to a player,
 send all passenger/vehicles to the player in the chain.
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index d1f07bbbd..945f06c93 100644
+index a3e9ee052..9b01c23e0 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Entity-fromMobSpawner.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Entity#fromMobSpawner()
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index b4233df5f..00791faf2 100644
+index 5a4de30fe..2dbb88f2d 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Make-entities-look-for-hoppers.patch

@@ -133,7 +133,7 @@ index 008ed206d..b3c1f550c 100644
              this.b = i;
              this.c = j;
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index cb9ef622c..c675a6e16 100644
+index 0a62ebf4a..0950c315f 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Option-to-use-vanilla-per-world-scoreboard-coloring-.patch

@@ -19,7 +19,7 @@ index abc1aabdd..6ea608ba9 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index e2202ed0c..88faa4601 100644
+index 87b82f908..fa9319aff 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Optional-TNT-doesn-t-move-in-water.patch

@@ -32,7 +32,7 @@ index 067cb233e..06acdaaf0 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index c105dd9b0..334441ed7 100644
+index 9b01c23e0..0a62ebf4a 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Properly-remove-entities-on-dimension-teleport.patch

@@ -22,7 +22,7 @@ requirement, but plugins (such as my own) use this method to
 trigger a "reload" of the entity on the client.
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 7b17c32bb..d03e7c24f 100644
+index 2dbb88f2d..80ecdb282 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper
@@ -35,14 +35,14 @@ index 7b17c32bb..d03e7c24f 100644
              this.world.methodProfiler.a("reposition");
              /* CraftBukkit start - Handled in calculateTarget
 diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
-index 49019d54d..9fe5c4406 100644
+index 49019d54d..bba2e164f 100644
 --- a/src/main/java/net/minecraft/server/WorldServer.java
 +++ b/src/main/java/net/minecraft/server/WorldServer.java
 @@ -0,0 +0,0 @@ public class WorldServer extends World implements IAsyncTaskHandler {
      }
  
      protected void c(Entity entity) {
-+        if (!entity.valid) return; // Paper - Already removed, dont fire twice - this looks like it can happen even without our changes
++        if (!this.entitiesByUUID.containsKey(entity.getUniqueID()) && !entity.valid) return; // Paper - Already removed, dont fire twice - this looks like it can happen even without our changes
          super.c(entity);
          this.entitiesById.d(entity.getId());
          this.entitiesByUUID.remove(entity.getUniqueID());

Spigot-Server-Patches/Use-a-Shared-Random-for-Entities.patch

@@ -6,14 +6,27 @@ Subject: [PATCH] Use a Shared Random for Entities
 Reduces memory usage and provides ensures more randomness, Especially since a lot of garbage entity objects get created.
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index b4ad611fc..4a08db5ba 100644
+index f547dbfd0..daf97bce3 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper
  
      // CraftBukkit start
      private static final int CURRENT_LEVEL = 2;
-+    public static Random SHARED_RANDOM = new Random(); // Paper
++    // Paper start
++    public static Random SHARED_RANDOM = new Random() {
++        private boolean locked = false;
++        @Override
++        public synchronized void setSeed(long seed) {
++            if (locked) {
++                LogManager.getLogger().error("Ignoring setSeed on Entity.SHARED_RANDOM", new Throwable());
++            } else {
++                super.setSeed(seed);
++                locked = true;
++            }
++        }
++    };
++    // Paper end
      static boolean isLevelAtLeast(NBTTagCompound tag, int level) {
          return tag.hasKey("Bukkit.updateLevel") && tag.getInt("Bukkit.updateLevel") >= level;
      }

Spigot-Server-Patches/Vanished-players-don-t-have-rights.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Vanished players don't have rights
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index f71528b5f..b13830e87 100644
+index d79844a98..6d1e61e23 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Vehicle-Event-Cancellation-Changes.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Vehicle Event Cancellation Changes
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 88faa4601..aece54d26 100644
+index fa9319aff..a3e9ee052 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper