Fix QueryParam Bug (#26)

* Fix bug when building query params

* Update version number

Author: scottoffen

src/FluentHttpClient/FluentHttpClient.csproj

@@ -15,7 +15,7 @@
     <PackageTags>fluent httpclient rest http api web client</PackageTags>
     <AssemblyVersion>$(Version)</AssemblyVersion>
     <FileVersion>$(Version)</FileVersion>
-    <Version>4.2.2</Version>
+    <Version>4.2.3</Version>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageReadmeFile>README.md</PackageReadmeFile>

src/FluentHttpClient/IEnumerableExtensions.cs

@@ -15,6 +15,8 @@ internal static class ListExtensions
     /// <returns></returns>
     public static string ToQueryString(this List<string> collection)
     {
-        return $"?{string.Join("&", collection)}";
+        return (collection.Count == 0)
+            ? string.Empty
+            : $"?{string.Join("&", collection)}";
     }
 }