Inject UriComponentsBuilder relative to webapp root

Issue: SPR-16813

Author: rstoyanchev

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ServerWebExchangeArgumentResolver.java

@@ -16,6 +16,7 @@
 
 package org.springframework.web.reactive.result.method.annotation;
 
+import java.net.URI;
 import java.time.ZoneId;
 import java.util.Locale;
 import java.util.TimeZone;
@@ -109,7 +110,8 @@ else if (ZoneId.class == paramType) {
 			return timeZone != null ? timeZone.toZoneId() : ZoneId.systemDefault();
 		}
 		else if (UriBuilder.class == paramType || UriComponentsBuilder.class == paramType) {
-			return UriComponentsBuilder.fromHttpRequest(exchange.getRequest());
+			URI uri = exchange.getRequest().getURI();
+			return UriComponentsBuilder.fromUri(uri).replacePath(null).replaceQuery(null);
 		}
 		else {
 			// should never happen...

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ServerWebExchangeArgumentResolverTests.java

@@ -20,6 +20,7 @@
 import java.util.Locale;
 import java.util.TimeZone;
 
+import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Mono;
 
@@ -52,7 +53,8 @@ public class ServerWebExchangeArgumentResolverTests {
 	private final ServerWebExchangeArgumentResolver resolver =
 			new ServerWebExchangeArgumentResolver(ReactiveAdapterRegistry.getSharedInstance());
 
-	private final MockServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/path"));
+	private final MockServerWebExchange exchange = MockServerWebExchange.from(
+			MockServerHttpRequest.get("http://example.org:9999/path?q=foo"));
 
 	private ResolvableMethod testMethod = ResolvableMethod.on(getClass()).named("handle").build();
 
@@ -103,7 +105,7 @@ public void resolveUriComponentsBuilder() throws Exception {
 
 		assertNotNull(value);
 		assertEquals(UriComponentsBuilder.class, value.getClass());
-		assertEquals("/path/next", ((UriComponentsBuilder) value).path("/next").build().toUriString());
+		assertEquals("http://example.org:9999/next", ((UriComponentsBuilder) value).path("/next").toUriString());
 	}