Adds getScheme()

spring-cloud-commons/src/main/java/org/springframework/cloud/client/ServiceInstance.java

@@ -54,4 +54,11 @@ public interface ServiceInstance {
 	 * @return the key value pair metadata associated with the service instance
 	 */
 	Map<String, String> getMetadata();
+
+	/**
+	 * @return the scheme of the instance
+	 */
+	default String getScheme() {
+		return null;
+	}
 }