Testing by css selector in an API test

I’m trying to test an http return that has an xforwarded for header added to it. Basically when we have this header set to a certain IP text appears on the website and we’d like to create a test to verify this is working. This is what I have so far.

def response = WS.sendRequest(findTestObject(‘XForwardedFor’))

WS.verifyElementText(response, ???, “Silverchair Test Institution”)

My question is how do I test that the text in .institution CSS selector is “Test Institution” . Because it’s a WS response is there no way to use CSS selector? if not how can I test the specific location this text appears? Additionally is there a different way to add headers to a normal webui request in order to test this functionality?

could you paste the request’s response here? It will be helpful to create the proper verification.