fix: PrefabHash not being saved in Unity >= 2018.3

Author: TwoTenPvP

MLAPI/Core/NetworkedObject.cs

@@ -24,11 +24,15 @@ namespace MLAPI
     public sealed class NetworkedObject : MonoBehaviour
     {
         private void OnValidate()
+        {
+            // Set this so the hash can be serialized on Scene objects. For prefabs, they are generated at runtime.
+            ValidateHash();
+        }
+
+        internal void ValidateHash()
         {
             if (string.IsNullOrEmpty(PrefabHashGenerator))
             {
-                PrefabHash = 0;
-                if (LogHelper.CurrentLogLevel <= LogLevel.Normal) LogHelper.LogWarning("The NetworkedObject " + gameObject.name + " does not have a PrefabHashGenerator. It has been set to the gameObject name");
                 PrefabHashGenerator = gameObject.name;
             }
 

MLAPI/Core/NetworkingManager.cs

@@ -252,6 +252,10 @@ private void OnValidate()
                 NetworkConfig.RegisteredScenes.Add(SceneManager.GetActiveScene().name);
             }
 
+            for (int i = 0; i < NetworkConfig.NetworkedPrefabs.Count; i++)
+            {
+                NetworkConfig.NetworkedPrefabs[i].Prefab.GetComponent<NetworkedObject>().ValidateHash();
+            }
 
             // TODO: Show which two prefab generators that collide
             HashSet<ulong> hashes = new HashSet<ulong>();
@@ -348,6 +352,11 @@ private void Init(bool server)
             }
 
             NetworkSceneManager.SetCurrentSceneIndex();
+
+            for (int i = 0; i < NetworkConfig.NetworkedPrefabs.Count; i++)
+            {
+                NetworkConfig.NetworkedPrefabs[i].Prefab.GetComponent<NetworkedObject>().ValidateHash();
+            }
 
             NetworkConfig.NetworkTransport.Init();
         }