3061 Add nullability

src/Hl7.Fhir.Base/Hl7.Fhir.Base.csproj

@@ -8,6 +8,7 @@
 		<Title>Firely's HL7 FHIR SDK Base Class Library</Title>
 		<Description>Firely's HL7 FHIR SDK Base Class Library. Is a dependency for the FHIR release-specific NuGet packages and is usually not directly referenced.</Description>
 		<PackageTags>HL7;FHIR;Firely;SDK;BCL</PackageTags>
+		<RootNamespace>Hl7.Fhir</RootNamespace>
 	</PropertyGroup>
 
 	<ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.1'">

src/Hl7.Fhir.Base/Model/Base.Extensions.cs

@@ -1,10 +1,14 @@
+/*
+ * Copyright (c) 2025, Firely (info@fire.ly) and contributors
+ * See the file CONTRIBUTORS for details.
+ *
+ * This file is licensed under the BSD 3-Clause license
+ * available at https://raw.githubusercontent.com/FirelyTeam/firely-net-sdk/master/LICENSE
+ */
+
 #nullable enable
-using Hl7.Fhir.ElementModel;
-using Hl7.Fhir.Introspection;
-using Hl7.Fhir.Rest;
-using Hl7.Fhir.Utility;
+
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 

src/Hl7.Fhir.Base/Model/Bundle.cs

@@ -109,11 +109,11 @@ public Uri? Alternate
 
         private Uri? getLink(string rel)
         {
-            if (Link is null) return null;
+            if (!Link.Any()) return null;
 
             var entry = Link.FirstOrDefault(e => rel.Equals(e.Relation, StringComparison.OrdinalIgnoreCase));
 
-            return entry != null ? new Uri(entry.Url, UriKind.RelativeOrAbsolute) : null;
+            return entry?.Url != null ? new Uri(entry.Url, UriKind.RelativeOrAbsolute) : null;
         }
 
         private void setLink(string rel, Uri? uri)

src/Hl7.Fhir.Base/Model/Canonical.cs

@@ -128,23 +128,25 @@ public static Canonical ForCoreType(string typename)
     /// <summary>
     /// The version string of the canonical (if present).
     /// </summary>
-    public string? Version => splitCanonical(Value).version;
+    public string? Version => Value is null ? null : splitCanonical(Value).version;
 
     /// <summary>
     /// Optional anchor at the end of the canonical, without the '#' prefix.
     /// </summary>
-    public string? Fragment => splitCanonical(Value).fragment;
+    public string? Fragment => Value is null ? null : splitCanonical(Value).fragment;
 
     /// <summary>
     /// The uri part of the canonical, which is the canonical without the version indication.
     /// </summary>
-    public string? Uri => splitCanonical(Value).url;
+    public string? Uri => Value is null ? null : splitCanonical(Value).url;
 
     /// <summary>
     /// Converts the canonical to a <see cref="System.Uri" />.
     /// </summary>
     /// <returns></returns>
-    public Uri ToUri() => new(Value, UriKind.RelativeOrAbsolute);
+    public Uri ToUri() => new(
+        Value ?? throw new InvalidOperationException("Cannot turn a canonical without a value into a Uri"),
+        UriKind.RelativeOrAbsolute);
 
     /// <summary>
     /// Whether the canonical is a relative or an absolute uri.

src/Hl7.Fhir.Base/Model/CodeableReference.cs

@@ -43,7 +43,7 @@ public P.Concept ToSystemConcept() =>
                                             "and can therefore not be converted to a System Concept.");
 
     internal P.Concept? ToSystemConceptInternal() =>
-        ((P.IToSystemPrimitive)Concept)?.TryConvertToSystemType(out var result) == true ? (P.Concept)result : null;
+        ((P.IToSystemPrimitive?)Concept)?.TryConvertToSystemType(out var result) == true ? (P.Concept)result : null;
 
     /// <summary>
     /// Converts the reference part of this CodeableReference to a <see cref="P.String" />.