Update target frameworks for broader compatibility and add System.Text.Json package

Author: Clifftech123

Directory.Packages.props

@@ -10,6 +10,11 @@
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
   </ItemGroup>
 
+  <!-- Core Libraries (for .NET Standard support) -->
+  <ItemGroup>
+    <PackageVersion Include="System.Text.Json" Version="8.0.5" />
+  </ItemGroup>
+
   <!-- Microsoft Extensions -->
   <ItemGroup>
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="9.0.0" />

src/CountryData.Globalization.Hosting/CountryData.Globalization.Hosting.csproj

@@ -1,8 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <!-- Target Frameworks - Modern .NET -->
-    <TargetFrameworks>netstandard2.1;net8.0;net9.0;net10.0</TargetFrameworks>
+    <!-- Target Frameworks - Broad compatibility (.NET Standard 2.0 works with .NET Framework 4.6.1+, .NET Core 2.0+, Unity, Xamarin) -->
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net10.0</TargetFrameworks>
     <LangVersion>latest</LangVersion>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
@@ -46,7 +46,8 @@ Initial release v1.0.0:
 - AddCountryData() extension method
 - Singleton lifetime management for ICountryDataProvider
 - Full ASP.NET Core integration support
-- Multi-framework support (.NET Standard 2.1, .NET 8-10)
+- Multi-framework support (.NET Standard 2.0+, .NET 6, 8, 10)
+- Works with .NET Framework 4.6.1+, .NET Core 2.0+, Unity, Xamarin
     </PackageReleaseNotes>
 
     <!-- Package Icon (uncomment when you add an icon) -->

src/CountryData.Globalization/CountryData.Globalization.csproj

@@ -1,9 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <!-- Target Frameworks - Modern .NET -->
-    <TargetFrameworks>netstandard2.1;net8.0;net9.0;net10.0</TargetFrameworks>
-    <LangVersion>latest</LangVersion>
+    
+    <TargetFrameworks>netstandard2.0;net6.0;net8.0;net10.0</TargetFrameworks>
+\    <LangVersion>latest</LangVersion>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 
@@ -49,8 +49,9 @@ Initial release v1.0.0:
 - Full CultureInfo and RegionInfo integration
 - O(1) dictionary lookups with lazy-loaded caches
 - Thread-safe operations with immutable data collections
-- Zero external dependencies
-- Multi-framework support (.NET Standard 2.1, .NET 8-10)
+- Minimal external dependencies (only System.Text.Json)
+- Multi-framework support (.NET Standard 2.0+, .NET 6, 8, 10)
+- Works with .NET Framework 4.6.1+, .NET Core 2.0+, Unity, Xamarin
 - Built-in dependency injection support via CountryData.Globalization.Hosting package
     </PackageReleaseNotes>
 
@@ -97,6 +98,7 @@ Initial release v1.0.0:
 
   <!-- Package References from Central Package Management -->
   <ItemGroup>
+    <PackageReference Include="System.Text.Json" />
     <PackageReference Include="MinVer" PrivateAssets="All" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" PrivateAssets="All" />
   </ItemGroup>

src/CountryData.Globalization/Models/Country.cs

@@ -2,24 +2,24 @@
 {
     /// <summary>
     /// Represents a country with its associated data including ISO codes, names, phone codes, regions, and Unicode emoji flag.
-    /// 
+    ///
     /// </summary>
     public class Country
     {
         /// <summary>
         /// Gets or sets the full country name (e.g., "United States", "Canada", "Japan").
         /// </summary>
-        public required string CountryName { get; set; }
+        public string CountryName { get; set; } = string.Empty;
 
         /// <summary>
         /// Gets or sets the international phone code for the country (e.g., "+1", "+44", "+81").
         /// </summary>
-        public required string PhoneCode { get; set; }
+        public string PhoneCode { get; set; } = string.Empty;
 
         /// <summary>
         /// Gets or sets the ISO 3166-1 alpha-2 country code (e.g., "US", "CA", "JP").
         /// </summary>
-        public required string CountryShortCode { get; set; }
+        public string CountryShortCode { get; set; } = string.Empty;
 
         /// <summary>
         /// Gets or sets the Unicode emoji flag representing the country (e.g., "🇺🇸", "🇨🇦", "🇯🇵").

src/CountryData.Globalization/Models/Region.cs

@@ -8,7 +8,7 @@ public class Region
         /// <summary>
         /// Gets or sets the full region name (e.g., "California", "Ontario", "Tokyo").
         /// </summary>
-        public required string Name { get; set; }
+        public string Name { get; set; } = string.Empty;
 
         /// <summary>
         /// Gets or sets the region short code (e.g., "CA", "ON", "13").