Add HideInTypeMenuAttribute

Author: mackysoft

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/HideInTypeMenuAttribute.cs

@@ -0,0 +1,11 @@
+#if UNITY_2019_3_OR_NEWER
+using System;
+
+/// <summary>
+/// An attribute that hides the type in the SubclassSelector.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+public sealed class HideInTypeMenuAttribute : Attribute {
+
+}
+#endif