How to use code to set whitelistHosts?

` <messaging>
      <untrustedWebRequest>
        <whitelistHosts>
          <add name="localhost" />
        </whitelistHosts>
      </untrustedWebRequest>
    </messaging>`
In the project after it was unable to dynamically modify the .config file, may I ask how to modify whitelistHosts list when you run the program