We've found what we believe to be an issue where calls to HttpServletRequest#getServerName when the new performant HTTP connector has been enabled is returning a different value when it is not enabled.

With the connector not enabled the value would be along the lines of:
{version}.appspot.com

With the connector enabled it always returns:
0.0.0.0

This can be reproduced using the Google App Engine Standard Environment Samples for Java 17 Bundled Services sample application and logging the output of the call to HttpServletRequest#getServerName in one of the servlets.