Accounted for struct root instances when references are enabled.

src/ExtendedXmlSerializer/ExtensionModel/References/RootReferences.cs

@@ -1,5 +1,5 @@
-using System.Collections.Immutable;
 using ExtendedXmlSerializer.ContentModel.Format;
+using System.Collections.Immutable;
 
 namespace ExtendedXmlSerializer.ExtensionModel.References
 {
@@ -14,6 +14,11 @@ public RootReferences(IReferences references, IRootInstances root)
 			_root       = root;
 		}
 
-		public ImmutableArray<object> Get(IFormatWriter parameter) => _references.Get(_root.Get(parameter.Get()));
+		public ImmutableArray<object> Get(IFormatWriter parameter)
+		{
+			var root   = _root.Get(parameter.Get());
+			var result = root != null ? _references.Get(root) : ImmutableArray<object>.Empty;
+			return result;
+		}
 	}
 }

test/ExtendedXmlSerializer.Tests.ReportedIssues/Issue355Tests.cs

@@ -1,5 +1,6 @@
 using ExtendedXmlSerializer.Configuration;
 using ExtendedXmlSerializer.Tests.ReportedIssues.Support;
+using JetBrains.Annotations;
 using Xunit;
 
 namespace ExtendedXmlSerializer.Tests.ReportedIssues
@@ -39,6 +40,7 @@ public Outer(string a, string b, string c)
 
 		sealed class CombinedProfile : CompositeConfigurationProfile
 		{
+			[UsedImplicitly]
 			public static CombinedProfile Default { get; } = new CombinedProfile();
 
 			CombinedProfile() : base(OuterProfile.Default) {}

test/ExtendedXmlSerializer.Tests.ReportedIssues/Issue358Tests.cs

@@ -0,0 +1,48 @@
+using ExtendedXmlSerializer.Configuration;
+using ExtendedXmlSerializer.Tests.ReportedIssues.Support;
+using FluentAssertions;
+using Xunit;
+
+namespace ExtendedXmlSerializer.Tests.ReportedIssues
+{
+	public sealed class Issue358Tests
+	{
+		[Fact]
+		void Verify()
+		{
+			var serializer = new ConfigurationContainer()
+			                 .EnableParameterizedContentWithPropertyAssignments()
+			                 .EnableReferences()
+			                 .Create()
+			                 .ForTesting();
+
+			var instance = new vector(new length(11), new length(13));
+
+			var cycled = serializer.Cycle(instance);
+			cycled.L1.Value.Should().Be(instance.L1.Value);
+			cycled.L2.Value.Should().Be(instance.L2.Value);
+		}
+
+		class length
+		{
+			public length(int value)
+			{
+				Value = value;
+			}
+
+			public int Value { get; }
+		}
+
+		private struct vector
+		{
+			public vector(length l1, length l2)
+			{
+				L1 = l1;
+				L2 = l2;
+			}
+
+			public length L1 { get; }
+			public length L2 { get; }
+		}
+	}
+}