Expose enableFallback property

Add an extra property to control the support of fallback resolution for
mobile views.

Fixes gh-3009, gh-3019

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mobile/DeviceDelegatingViewResolverAutoConfiguration.java

 /*
- * Copyright 2012-2014 the original author or authors.
+ * Copyright 2012-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -64,6 +64,7 @@ public class DeviceDelegatingViewResolverAutoConfiguration {
 				ViewResolver delegate, int delegateOrder) {
 			LiteDeviceDelegatingViewResolver resolver = new LiteDeviceDelegatingViewResolver(
 					delegate);
+			resolver.setEnableFallback(this.viewResolverProperties.isEnableFallback());
 			resolver.setNormalPrefix(this.viewResolverProperties.getNormalPrefix());
 			resolver.setNormalSuffix(this.viewResolverProperties.getNormalSuffix());
 			resolver.setMobilePrefix(this.viewResolverProperties.getMobilePrefix());

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mobile/DeviceDelegatingViewResolverProperties.java

 /*
- * Copyright 2012-2014 the original author or authors.
+ * Copyright 2012-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,11 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
 @ConfigurationProperties("spring.mobile.devicedelegatingviewresolver")
 public class DeviceDelegatingViewResolverProperties {
 
+	/**
+	 * Enable support for fallback resolution.
+	 */
+	private boolean enableFallback;
+
 	/**
 	 * Prefix that gets prepended to view names for normal devices.
 	 */
@@ -57,6 +62,14 @@ public class DeviceDelegatingViewResolverProperties {
 	 */
 	private String tabletSuffix = "";
 
+	public void setEnableFallback(boolean enableFallback) {
+		this.enableFallback = enableFallback;
+	}
+
+	public boolean isEnableFallback() {
+		return enableFallback;
+	}
+
 	public String getNormalPrefix() {
 		return this.normalPrefix;
 	}

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -497,6 +497,7 @@ content into your application; rather pick only the properties that you need.
 
 	# SPRING MOBILE DEVICE VIEWS ({sc-spring-boot-autoconfigure}/mobile/DeviceDelegatingViewResolverAutoConfiguration.{sc-ext}[DeviceDelegatingViewResolverAutoConfiguration])
 	spring.mobile.devicedelegatingviewresolver.enabled=true # disabled by default
+	spring.mobile.devicedelegatingviewresolver.enable-fallback= # enable support for fallback resolution, default to false.
 	spring.mobile.devicedelegatingviewresolver.normal-prefix=
 	spring.mobile.devicedelegatingviewresolver.normal-suffix=
 	spring.mobile.devicedelegatingviewresolver.mobile-prefix=mobile/