com.unity.netcode.gameobjects@1.5.1

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

Additional documentation and release notes are available at [Multiplayer Documentation](https://docs-multiplayer.unity3d.com).

## [1.5.1] - 2023-06-07

### Added

- Added support for serializing `NativeArray<>` and `NativeList<>` in `FastBufferReader`/`FastBufferWriter`, `BufferSerializer`, `NetworkVariable`, and RPCs. (To use `NativeList<>`, add `UNITY_NETCODE_NATIVE_COLLECTION_SUPPORT` to your Scripting Define Symbols in `Project Settings > Player`) (#2375)
- The location of the automatically-created default network prefab list can now be configured (#2544)
- Added: Message size limits (max single message and max fragmented message) can now be set using NetworkManager.MaximumTransmissionUnitSize and NetworkManager.MaximumFragmentedMessageSize for transports that don't work with the default values (#2530)
- Added `NetworkObject.SpawnWithObservers` property (default is true) that when set to false will spawn a `NetworkObject` with no observers and will not be spawned on any client until `NetworkObject.NetworkShow` is invoked. (#2568)

### Fixed

- Fixed: Fixed a null reference in codegen in some projects (#2581)
- Fixed issue where the `OnClientDisconnected` client identifier was incorrect after a pending client connection was denied. (#2569)
- Fixed warning "Runtime Network Prefabs was not empty at initialization time." being erroneously logged when no runtime network prefabs had been added (#2565)
- Fixed issue where some temporary debug console logging was left in a merged PR. (#2562)
- Fixed the "Generate Default Network Prefabs List" setting not loading correctly and always reverting to being checked. (#2545)
- Fixed issue where users could not use NetworkSceneManager.VerifySceneBeforeLoading to exclude runtime generated scenes from client synchronization. (#2550)
- Fixed missing value on `NetworkListEvent` for `EventType.RemoveAt` events.  (#2542,#2543)
- Fixed issue where parenting a NetworkTransform under a transform with a scale other than Vector3.one would result in incorrect values on non-authoritative instances. (#2538)
- Fixed issue where a server would include scene migrated and then despawned NetworkObjects to a client that was being synchronized. (#2532)
- Fixed the inspector throwing exceptions when attempting to render `NetworkVariable`s of enum types. (#2529)
- Making a `NetworkVariable` with an `INetworkSerializable` type that doesn't meet the `new()` constraint will now create a compile-time error instead of an editor crash (#2528)
- Fixed Multiplayer Tools package installation docs page link on the NetworkManager popup. (#2526)
- Fixed an exception and error logging when two different objects are shown and hidden on the same frame (#2524)
- Fixed a memory leak in `UnityTransport` that occurred if `StartClient` failed. (#2518)
- Fixed issue where a client could throw an exception if abruptly disconnected from a network session with one or more spawned `NetworkObject`(s). (#2510)
- Fixed issue where invalid endpoint addresses were not being detected and returning false from NGO UnityTransport. (#2496)
- Fixed some errors that could occur if a connection is lost and the loss is detected when attempting to write to the socket. (#2495)

## Changed

- Adding network prefabs before NetworkManager initialization is now supported. (#2565)
- Connecting clients being synchronized now switch to the server's active scene before spawning and synchronizing NetworkObjects. (#2532)
- Updated `UnityTransport` dependency on `com.unity.transport` to 1.3.4. (#2533)
- Improved performance of NetworkBehaviour initialization by replacing reflection when initializing NetworkVariables with compile-time code generation, which should help reduce hitching during additive scene loads. (#2522)

Runtime/Messaging/IDeferredNetworkMessageManager.cs

@@ -0,0 +1,35 @@
+namespace Unity.Netcode
+{
+    internal interface IDeferredNetworkMessageManager
+    {
+        internal enum TriggerType
+        {
+            OnSpawn,
+            OnAddPrefab,
+        }
+
+        /// <summary>
+        /// Defers processing of a message until the moment a specific networkObjectId is spawned.
+        /// This is to handle situations where an RPC or other object-specific message arrives before the spawn does,
+        /// either due to it being requested in OnNetworkSpawn before the spawn call has been executed
+        ///
+        /// There is a one second maximum lifetime of triggers to avoid memory leaks. After one second has passed
+        /// without the requested object ID being spawned, the triggers for it are automatically deleted.
+        /// </summary>
+        void DeferMessage(TriggerType trigger, ulong key, FastBufferReader reader, ref NetworkContext context);
+
+        /// <summary>
+        /// Cleans up any trigger that's existed for more than a second.
+        /// These triggers were probably for situations where a request was received after a despawn rather than before a spawn.
+        /// </summary>
+        void CleanupStaleTriggers();
+
+        void ProcessTriggers(TriggerType trigger, ulong key);
+
+        /// <summary>
+        /// Cleans up any trigger that's existed for more than a second.
+        /// These triggers were probably for situations where a request was received after a despawn rather than before a spawn.
+        /// </summary>
+        void CleanupAllTriggers();
+    }
+}