Fix code analysis violations

Author: Chris Martinez

src/Microsoft.AspNetCore.Mvc.Versioning/Routing/ApiVersionLinkGenerator.cs

@@ -24,7 +24,7 @@ public class ApiVersionLinkGenerator : LinkGenerator
         protected LinkGenerator LinkGenerator { get; }
 
         /// <inheritdoc />
-        public override string GetPathByAddress<TAddress>(
+        public override string? GetPathByAddress<TAddress>(
             HttpContext httpContext,
             TAddress address,
             RouteValueDictionary values,
@@ -38,15 +38,15 @@ public override string GetPathByAddress<TAddress>(
         }
 
         /// <inheritdoc />
-        public override string GetPathByAddress<TAddress>(
+        public override string? GetPathByAddress<TAddress>(
             TAddress address,
             RouteValueDictionary values,
             PathString pathBase = default,
             FragmentString fragment = default,
             LinkOptions? options = null ) => LinkGenerator.GetPathByAddress( address, values, pathBase, fragment, options );
 
         /// <inheritdoc />
-        public override string GetUriByAddress<TAddress>(
+        public override string? GetUriByAddress<TAddress>(
             HttpContext httpContext,
             TAddress address,
             RouteValueDictionary values,
@@ -62,7 +62,7 @@ public override string GetUriByAddress<TAddress>(
         }
 
         /// <inheritdoc />
-        public override string GetUriByAddress<TAddress>(
+        public override string? GetUriByAddress<TAddress>(
             TAddress address,
             RouteValueDictionary values,
             string scheme,

src/Microsoft.AspNetCore.Mvc.Versioning/Versioning/Conventions/ControllerApiVersionConventionBuilder.cs

@@ -21,8 +21,7 @@ protected override bool TryGetConvention( MethodInfo method, [NotNullWhen( true
         {
             if ( ActionBuilders.TryGetValue( method, out var actionBuilder ) )
             {
-                convention = actionBuilder;
-                return true;
+                return ( convention = actionBuilder ) != null;
             }
 
             convention = default;

src/Shared/TypeExtensions.cs

@@ -112,10 +112,10 @@ static void ProcessGenericType( StringBuilder builder, Type type, Type[] generic
                 }
             }
 
-#if NETCOREAPP3_1
-            var genericPartIndex = type.Name.IndexOf( '`', StringComparison.Ordinal );
-#else
+#if WEBAPI
             var genericPartIndex = type.Name.IndexOf( '`' );
+#else
+            var genericPartIndex = type.Name.IndexOf( '`', StringComparison.Ordinal );
 #endif
 
             if ( genericPartIndex <= 0 )