When ResourceConfigurationPage.updateResource() was updated to use a lambda expersion, it was limited to visit TextField.class for no clear reason. This means that the method will only visit children that are TextFields, and therfore no longer has any effect.
See here for the commit in question.
Pull request: https://github.com/geoserver/geoserver/pull/1673
Mass closing all resolved issues not modified in the last 4 weeks