Don't make assumptions about the UriTemplateHandler

Fixes gh-115

spring-cloud-gateway-mvc/pom.xml

@@ -25,6 +25,11 @@
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-actuator</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-configuration-processor</artifactId>

spring-cloud-gateway-mvc/src/main/java/org/springframework/cloud/gateway/mvc/ProxyExchange.java

@@ -66,7 +66,6 @@
 import org.springframework.web.method.support.ModelAndViewContainer;
 import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor;
-import org.springframework.web.util.AbstractUriTemplateHandler;
 
 /**
  * A <code>@RequestMapping</code> argument type that can proxy the request to a backend.
@@ -463,9 +462,7 @@ private NestedTemplate createTemplate(RestTemplate input) {
 		NestedTemplate rest = new NestedTemplate();
 		rest.setMessageConverters(input.getMessageConverters());
 		rest.setErrorHandler(input.getErrorHandler());
-		rest.setDefaultUriVariables(
-				((AbstractUriTemplateHandler) input.getUriTemplateHandler())
-						.getDefaultUriVariables());
+		rest.setUriTemplateHandler(input.getUriTemplateHandler());
 		rest.setRequestFactory(input.getRequestFactory());
 		rest.setInterceptors(input.getInterceptors());
 		return rest;