Error "The root element must match the name of the section referencing the file", when root element does match the name of the section

I am trying to move appSettings config section to an external file using "file" attribute and keep getting the error:

System.Configuration.ConfigurationErrorsException : The root element must match the name of the section referencing the file, 'appSettings'

The problem is that root element in the external file is already 'appSettings'. Tried using root 'configuration' and custom config Sections, and it didn't help either

External file Test.config is below

<?xml version="1.0" encoding="utf-8" ?>
<appSettings>
  <add key="URL" value="https://www.google.com" />
</appSettings>

Main App.config file

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="specFlow" type="TechTalk.SpecFlow.Configuration.ConfigurationSectionHandler, TechTalk.SpecFlow"/>
  </configSections>
  <specFlow>
    <!-- For additional details on SpecFlow configuration options see http://go.specflow.org/doc-config -->
  </specFlow>
  <appSettings file="Test.config"/>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral"/>
        <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0"/>
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1"/>
</startup>
</configuration>

Can anyone help me with this?

Thank you.