Feign client builder should not assume all annotations are the same

Simple solution is to check for instanceof before casting.

Fixes gh-265

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/support/SpringMvcContract.java

@@ -45,6 +45,9 @@ public class SpringMvcContract extends Contract.BaseContract {
 	@Override
 	protected void processAnnotationOnMethod(MethodMetadata data,
 			Annotation methodAnnotation, Method method) {
+		if (!(methodAnnotation instanceof RequestMapping)) {
+			return;
+		}
 		RequestMapping mapping = RequestMapping.class.cast(methodAnnotation);
 		if (mapping != null) {
 			// HTTP Method

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/valid/FeignClientValidationTests.java

@@ -46,6 +46,7 @@ public class FeignClientValidationTests {
 		@FeignClient("foo")
 		interface Client {
 			@RequestMapping(method = RequestMethod.GET, value = "/")
+			@Deprecated
 			String get();
 		}