FIX: Device capability matching fails when registering a layout using JSON device.capabilities (#2368)

Author: Shaolin-Hari

Assets/Tests/InputSystem/CoreTests_Layouts.cs

@@ -499,6 +499,40 @@ public void Layouts_CanFindLayoutFromDeviceDescription()
         Assert.That(layout, Is.EqualTo("MyDevice"));
     }
 
+    [Test]
+    [Category("Layouts")]
+    public void Layouts_CanMatchLayoutBasedOnCapabilitiesFromJson()
+    {
+        const string json = @"
+     {
+         ""name"" : ""CapabilityTestLayout"",
+         ""extend"" : ""Gamepad"",
+         ""device"" : {
+             ""capabilities"" : [
+                 { ""path"" : ""vendorId"", ""value"" : ""9999"" }
+             ]
+         }
+     }";
+
+        InputSystem.RegisterLayout(json);
+
+        try
+        {
+            var matchedLayout = InputSystem.TryFindMatchingLayout(
+                new InputDeviceDescription
+                {
+                    deviceClass = "Gamepad",
+                    capabilities = @"{""vendorId"":""9999""}"
+                });
+
+            Assert.That(matchedLayout, Is.EqualTo("CapabilityTestLayout"));
+        }
+        finally
+        {
+            InputSystem.RemoveLayout("CapabilityTestLayout");
+        }
+    }
+
     [Test]
     [Category("Layouts")]
     public void Layouts_CanFindAllLayoutsBasedOnGivenLayout()

Packages/com.unity.inputsystem/InputSystem/Devices/InputDeviceMatcher.cs

@@ -564,6 +564,7 @@ internal struct MatcherJson
             public string[] versions;
             public Capability[] capabilities;
 
+            [Serializable]
             public struct Capability
             {
                 public string path;