Order char encoding filter so it sets encoding before request is read

For the character encoding filter to work, it's vital that it sets
the request's encoding before any other filters attempt to read the
request. This commit updates the order of
OrderedCharacterEncodingFilter to be HIGHEST_PRECEDENCE and improves
the existing test to check that the ordering is as required.

Closes gh-3912

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/HttpEncodingAutoConfigurationTests.java

@@ -27,6 +27,8 @@
 import org.junit.rules.ExpectedException;
 import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.boot.context.web.OrderedHiddenHttpMethodFilter;
+import org.springframework.boot.context.web.OrderedHttpPutFormContentFilter;
 import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -145,8 +147,13 @@ public CharacterEncodingFilter myCharacterEncodingFilter() {
 	static class OrderedConfiguration {
 
 		@Bean
-		public HiddenHttpMethodFilter hiddenHttpMethodFilter() {
-			return new HiddenHttpMethodFilter();
+		public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {
+			return new OrderedHiddenHttpMethodFilter();
+		}
+
+		@Bean
+		public OrderedHttpPutFormContentFilter httpPutFormContentFilter() {
+			return new OrderedHttpPutFormContentFilter();
 		}
 
 	}

spring-boot/src/main/java/org/springframework/boot/context/web/OrderedCharacterEncodingFilter.java

@@ -16,7 +16,6 @@
 
 package org.springframework.boot.context.web;
 
-import org.springframework.boot.context.embedded.FilterRegistrationBean;
 import org.springframework.core.Ordered;
 import org.springframework.web.filter.CharacterEncodingFilter;
 
@@ -29,7 +28,7 @@
 public class OrderedCharacterEncodingFilter extends CharacterEncodingFilter implements
 		Ordered {
 
-	private int order = FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER - 9800;
+	private int order = Ordered.HIGHEST_PRECEDENCE;
 
 	@Override
 	public int getOrder() {