Support encodeUrl mechanism via ServerHttpResponse

Issue: SPR-14529

spring-web/src/test/java/org/springframework/http/server/reactive/ServerHttpResponseTests.java

@@ -42,6 +42,27 @@ import static org.junit.Assert.assertSame;
  */
 public class ServerHttpResponseTests {
 
+	@Test
+	public void encodeUrlDefault() throws Exception {
+		TestServerHttpResponse response = new TestServerHttpResponse();
+		assertEquals("/foo", response.encodeUrl("/foo"));
+	}
+
+	@Test
+	public void encodeUrlWithEncoder() throws Exception {
+		TestServerHttpResponse response = new TestServerHttpResponse();
+		response.registerUrlEncoder(s -> s + "?nonce=123");
+		assertEquals("/foo?nonce=123", response.encodeUrl("/foo"));
+	}
+
+	@Test
+	public void encodeUrlWithMultipleEncoders() throws Exception {
+		TestServerHttpResponse response = new TestServerHttpResponse();
+		response.registerUrlEncoder(s -> s + ";p=abc");
+		response.registerUrlEncoder(s -> s + "?q=123");
+		assertEquals("/foo;p=abc?q=123", response.encodeUrl("/foo"));
+	}
+
 	@Test
 	public void writeWith() throws Exception {
 		TestServerHttpResponse response = new TestServerHttpResponse();

spring-web/src/test/java/org/springframework/mock/http/server/reactive/test/MockServerHttpResponse.java

@@ -18,6 +18,7 @@ package org.springframework.mock.http.server.reactive.test;
 
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.reactivestreams.Publisher;
@@ -49,6 +50,8 @@ public class MockServerHttpResponse implements ServerHttpResponse {
 
 	private final MultiValueMap<String, ResponseCookie> cookies = new LinkedMultiValueMap<>();
 
+	private Function<String, String> urlEncoder = url -> url;
+
 	private Flux<DataBuffer> body;
 
 	private Flux<Publisher<DataBuffer>> bodyWithFlushes;
@@ -77,6 +80,16 @@ public class MockServerHttpResponse implements ServerHttpResponse {
 		return this.cookies;
 	}
 
+	@Override
+	public String encodeUrl(String url) {
+		return (this.urlEncoder != null ? this.urlEncoder.apply(url) : url);
+	}
+
+	@Override
+	public void registerUrlEncoder(Function<String, String> encoder) {
+		this.urlEncoder = (this.urlEncoder != null ? this.urlEncoder.andThen(encoder) : encoder);
+	}
+
 	public Publisher<DataBuffer> getBody() {
 		return this.body;
 	}