ISPConfig3 Domain points to a subdirectory of Web

Question

Have a DocRoot /var/www/clients/client2/web4/web and the domain mytest.tld should point to a directory /var/www/clients/client2/web4/web/public. The DocRoot should not be changed. How can I make the domain point to the /public subdirectory?

THANKS

I tried to work with the Apache directives. Unfortunately it did not work.