Change default order of AutoConfigureOrder to 0

Previously, AutoConfigureOrder defaulted to Ordered.LOWEST_PRECEDENCE.
This made is impossible for an individual auto-configuration to
indicate that it wanted to go "last", i.e. after any
auto-configuration classes that didn't not specify an order, or
specified an order other than LOWEST_PRECEDENCE.

This commit changes to default to 0, allowing a single
 auto-configuration to easily indicate that it should go last.

 Closes gh-10142

Author: wilkinsona

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AutoConfigurationSorter.java

@@ -26,7 +26,6 @@
 import java.util.Map;
 import java.util.Set;
 
-import org.springframework.core.Ordered;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.core.type.classreading.MetadataReader;
 import org.springframework.core.type.classreading.MetadataReaderFactory;
@@ -164,11 +163,11 @@ public Set<String> getAfter() {
 		private int getOrder() {
 			if (wasProcessed()) {
 				return this.autoConfigurationMetadata.getInteger(this.className,
-						"AutoConfigureOrder", Ordered.LOWEST_PRECEDENCE);
+						"AutoConfigureOrder", AutoConfigureOrder.DEFAULT_ORDER);
 			}
 			Map<String, Object> attributes = getAnnotationMetadata()
 					.getAnnotationAttributes(AutoConfigureOrder.class.getName());
-			return (attributes == null ? Ordered.LOWEST_PRECEDENCE
+			return (attributes == null ? AutoConfigureOrder.DEFAULT_ORDER
 					: (Integer) attributes.get("value"));
 		}
 

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AutoConfigureOrder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -38,11 +38,13 @@
 @Target({ ElementType.TYPE, ElementType.METHOD, ElementType.FIELD })
 public @interface AutoConfigureOrder {
 
+	int DEFAULT_ORDER = 0;
+
 	/**
-	 * The order value. Default is {@link Ordered#LOWEST_PRECEDENCE}.
+	 * The order value. Default is {@code 0}.
 	 * @see Ordered#getOrder()
 	 * @return the order value
 	 */
-	int value() default Ordered.LOWEST_PRECEDENCE;
+	int value() default DEFAULT_ORDER;
 
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/AutoConfigurationSorterTests.java

@@ -40,9 +40,12 @@
  * Tests for {@link AutoConfigurationSorter}.
  *
  * @author Phillip Webb
+ * @author Andy Wilkinson
  */
 public class AutoConfigurationSorterTests {
 
+	private static final String DEFAULT = OrderUnspecified.class.getName();
+
 	private static final String LOWEST = OrderLowest.class.getName();
 
 	private static final String HIGHEST = OrderHighest.class.getName();
@@ -86,8 +89,8 @@ public void setup() {
 	@Test
 	public void byOrderAnnotation() throws Exception {
 		List<String> actual = this.sorter
-				.getInPriorityOrder(Arrays.asList(LOWEST, HIGHEST));
-		assertThat(actual).containsExactly(HIGHEST, LOWEST);
+				.getInPriorityOrder(Arrays.asList(LOWEST, HIGHEST, DEFAULT));
+		assertThat(actual).containsExactly(HIGHEST, DEFAULT, LOWEST);
 	}
 
 	@Test
@@ -193,6 +196,11 @@ private String merge(Class<?>[] value, String[] name) {
 		return StringUtils.collectionToCommaDelimitedString(items);
 	}
 
+	@AutoConfigureOrder
+	public static class OrderUnspecified {
+
+	}
+
 	@AutoConfigureOrder(Ordered.LOWEST_PRECEDENCE)
 	public static class OrderLowest {