SPIGOT-5477: Server not shutting down

nms-patches/PlayerConnectionUtils.patch

@@ -8,3 +8,14 @@
                  if (t0.a().isConnected()) {
                      packet.a(t0);
                  } else {
+@@ -23,5 +24,10 @@
+             });
+             throw CancelledPacketHandleException.INSTANCE;
+         }
++        // CraftBukkit start - SPIGOT-5477, MC-142590
++        else if (MinecraftServer.getServer().hasStopped() || (t0 instanceof PlayerConnection && ((PlayerConnection) t0).processedDisconnect)) {
++            throw CancelledPacketHandleException.INSTANCE;
++        }
++        // CraftBukkit end
+     }
+ }