Xml files found some items when the package will not be packaged into the core project, how to do?

I found a file package after package folder, xml file does not exist, so swagger load failed; then been tested and found items Core package is the default when not included Xml file, VS there is no way to set.

Workaround : manually modify the project file, locate the project file that you want to generate xml project file .csproj, adding this sentence in <PropertyGroup> node

    <GenerateDocumentationFile>true</GenerateDocumentationFile>