nuget package .pp not transform to .cs file

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: