Make RequestMappingHandlerMapping @Primary

Update WebMvcAutoConfiguration so that the RequestMappingHandlerMapping
bean is @Primary. Prior to this commit a NoUniqueBeanDefinitionException
would be thrown then using the MvcUriComponentsBuilder.

Fixes gh-2237

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration.java

@@ -41,6 +41,8 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplicat
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.context.annotation.Primary;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
 import org.springframework.core.convert.converter.Converter;
@@ -62,6 +64,7 @@ import org.springframework.web.servlet.DispatcherServlet;
 import org.springframework.web.servlet.LocaleResolver;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.ViewResolver;
+import org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
 import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
 import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
@@ -69,6 +72,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupp
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
 import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;
 import org.springframework.web.servlet.i18n.FixedLocaleResolver;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
 import org.springframework.web.servlet.resource.ResourceHttpRequestHandler;
 import org.springframework.web.servlet.view.BeanNameViewResolver;
 import org.springframework.web.servlet.view.ContentNegotiatingViewResolver;
@@ -127,7 +131,7 @@ public class WebMvcAutoConfiguration {
 	// Defined as a nested config to ensure WebMvcConfigurerAdapter is not read when not
 	// on the classpath
 	@Configuration
-	@EnableWebMvc
+	@Import(EnableWebMvcConfiguration.class)
 	@EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })
 	public static class WebMvcAutoConfigurationAdapter extends WebMvcConfigurerAdapter {
 
@@ -304,4 +308,20 @@ public class WebMvcAutoConfiguration {
 
 	}
 
+	/**
+	 * Configuration equivalent to {@code @EnableWebMvc}.
+	 */
+	@Configuration
+	public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
+
+		@Bean
+		@Primary
+		@Override
+		public RequestMappingHandlerMapping requestMappingHandlerMapping() {
+			// Must be @Primary for MvcUriComponentsBuilder to work
+			return super.requestMappingHandlerMapping();
+		}
+
+	}
+
 }