WebFlux AbstractUrlHandlerMapping support URI vars

Closes gh-25648

spring-webflux/src/test/java/org/springframework/web/reactive/handler/SimpleUrlHandlerMappingTests.java

@@ -17,6 +17,8 @@
 package org.springframework.web.reactive.handler;
 
 import java.net.URI;
+import java.util.Collections;
+import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 
@@ -115,6 +117,19 @@ public class SimpleUrlHandlerMappingTests {
 		}
 	}
 
+	@Test
+	void uriTemplateVariables() {
+		Object handler = new Object();
+		SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
+		mapping.registerHandlers(Collections.singletonMap("/foo/{bar}/baz", handler));
+
+		ServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/foo/123/baz").build());
+		Object expected = mapping.getHandler(exchange).block();
+		assertThat(expected).isSameAs(handler);
+
+		Map<String, String> vars = exchange.getAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE);
+		assertThat(vars).isNotNull().containsEntry("bar", "123");
+	}
 
 	@Configuration
 	static class WebConfig {