Add nullable annotations to System.ComponentModel.TypeConverter

src/libraries/System.ComponentModel.Annotations/src/System/ComponentModel/DataAnnotations/MetadataPropertyDescriptorWrapper.cs

@@ -26,7 +26,7 @@ public MetadataPropertyDescriptorWrapper(PropertyDescriptor descriptor, Attribut
 
         public override Type ComponentType { get { return _descriptor.ComponentType; } }
 
-        public override object GetValue(object component) { return _descriptor.GetValue(component); }
+        public override object? GetValue(object? component) { return _descriptor.GetValue(component); }
 
         public override bool IsReadOnly
         {
@@ -45,7 +45,7 @@ public override bool IsReadOnly
 
         public override void ResetValue(object component) { _descriptor.ResetValue(component); }
 
-        public override void SetValue(object component, object value) { _descriptor.SetValue(component, value); }
+        public override void SetValue(object? component, object? value) { _descriptor.SetValue(component, value); }
 
         public override bool ShouldSerializeValue(object component) { return _descriptor.ShouldSerializeValue(component); }
 

src/libraries/System.ComponentModel.Annotations/src/System/ComponentModel/DataAnnotations/RangeAttribute.cs

@@ -207,11 +207,11 @@ private void SetupConversion()
 
                     TypeConverter converter = GetOperandTypeConverter();
                     IComparable min = (IComparable)(ParseLimitsInInvariantCulture
-                        ? converter.ConvertFromInvariantString((string)minimum)
-                        : converter.ConvertFromString((string)minimum));
+                        ? converter.ConvertFromInvariantString((string)minimum)!
+                        : converter.ConvertFromString((string)minimum))!;
                     IComparable max = (IComparable)(ParseLimitsInInvariantCulture
-                        ? converter.ConvertFromInvariantString((string)maximum)
-                        : converter.ConvertFromString((string)maximum));
+                        ? converter.ConvertFromInvariantString((string)maximum)!
+                        : converter.ConvertFromString((string)maximum))!;
 
                     Func<object, object?> conversion;
                     if (ConvertValueInInvariantCulture)

src/libraries/System.ComponentModel.TypeConverter/ref/System.ComponentModel.TypeConverter.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System.ComponentModel.manual.cs" />