WebTestClientHtmlUnitDriverBuilder uses WebTestClient for localhost

Fixes gh-4815

config/src/test/java/org/springframework/security/htmlunit/server/WebTestClientHtmlUnitDriverBuilder.java

@@ -17,8 +17,12 @@
 package org.springframework.security.htmlunit.server;
 
 import com.gargoylesoftware.htmlunit.WebClient;
+import com.gargoylesoftware.htmlunit.WebConnection;
 import org.openqa.selenium.WebDriver;
 import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.test.web.servlet.htmlunit.DelegatingWebConnection;
+import org.springframework.test.web.servlet.htmlunit.DelegatingWebConnection.DelegateWebConnection;
+import org.springframework.test.web.servlet.htmlunit.HostRequestMatcher;
 import org.springframework.test.web.servlet.htmlunit.webdriver.WebConnectionHtmlUnitDriver;
 
 /**
@@ -35,7 +39,8 @@ public class WebTestClientHtmlUnitDriverBuilder {
 	public WebDriver build() {
 		WebConnectionHtmlUnitDriver driver = new WebConnectionHtmlUnitDriver();
 		WebClient webClient = driver.getWebClient();
-		WebTestClientWebConnection connection = new WebTestClientWebConnection(this.webTestClient, webClient);
+		WebTestClientWebConnection webClientConnection = new WebTestClientWebConnection(this.webTestClient, webClient);
+		WebConnection connection = new DelegatingWebConnection(driver.getWebConnection(), new DelegateWebConnection(new HostRequestMatcher("localhost"), webClientConnection));
 		driver.setWebConnection(connection);
 		return driver;
 	}