nuget package .pp not transform to .cs file

Question

I am creating a NuGet package and I need to include some cs files and hope their namespace can auto transform to the target project's namespace. So I found the document said that I need to use .pp and replace the origin namespace to $rootname$. But when I publish this package, the target project not showing the Test.cs file in it, What am I missing?

Here are my Test.cs.pp, nuspec and nupkg screenshot

Test.cs.pp:

using $rootnamespace$.Enums;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Text;

namespace $rootnamespace$.Entities
{
    public class Test
    {
        public LogTypeEnum LogType { get; set; }
        [StringLength(60)]
        public string ClientIP { get; set; }
        [StringLength(512)]
        public string Method { get; set; }
        public string Params { get; set; }
        public string Message { get; set; }
        public string Exception { get; set; }
    }
}

nuspec:

<?xml version="1.0" encoding="utf-8"?>
<package >
  <metadata>
    <id>$id$</id>
    <version>1.0.51</version>
    <title>$title$</title>
    <authors>Nicky</authors>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <license type="expression">MIT</license>
    <!--<projectUrl>http://project_url_here_or_delete_this_line/</projectUrl>
    <iconUrl>http://icon_url_here_or_delete_this_line/</iconUrl>-->
    <description>Test</description>
    <releaseNotes>test</releaseNotes>
    <copyright>$copyright$</copyright>
    <dependencies>
        <group targetFramework=".NETCoreApp3.1">
            <dependency id="AutoMapper.Extensions.Microsoft.DependencyInjection" version="7.0.0" exclude="Build,Analyzers" />
            <dependency id="Microsoft.AspNetCore.Identity.EntityFrameworkCore" version="3.1.2" exclude="Build,Analyzers" />
            <dependency id="Microsoft.AspNetCore.Identity.UI" version="3.1.2" exclude="Build,Analyzers" />
            <dependency id="Microsoft.EntityFrameworkCore" version="3.1.2" exclude="Build,Analyzers" />
            <dependency id="Microsoft.EntityFrameworkCore.SqlServer" version="3.1.2" exclude="Build,Analyzers" />
            <dependency id="Microsoft.EntityFrameworkCore.Sqlite" version="3.1.2" exclude="Build,Analyzers" />
            <dependency id="Newtonsoft.Json" version="12.0.3" exclude="Build,Analyzers" />
        </group>
    </dependencies>
    <frameworkReferences>
        <group targetFramework=".NETCoreApp3.1">
            <frameworkReference name="Microsoft.AspNetCore.App" />
        </group>
    </frameworkReferences>
    <contentFiles>
        <!-- Include Assets as Content -->
        <files include="**/images/*.*" buildAction="EmbeddedResource" />
        <files include="cs/**/*.*" buildAction="Compile" />
        <files include="pp/**/*.*" buildAction="Compile" />
    </contentFiles>
  </metadata>

    <files>
        <!--<file src="contentFiles\**" target="contentFiles" />-->
        <file src="Entities\*.cs" target="contentFiles\cs\any\Entities" />
        <file src="Entities\*.pp" target="contentFiles\cs\any\Entities" />
    </files>
</package>

and nupkg: