Fix ordering of keys in PropertySourcesPropertyValues

Since @ConfigurationProperties binding uses a single instance of
PropertySourcesPropertyValues per bean, there doesn't seem to be
any issue with using a normal LinkedHashMap. Then the order
passed in as PropertySources will be preserved.

Fixes gh-2487

spring-boot/src/main/java/org/springframework/boot/bind/PropertySourcesPropertyValues.java

@@ -19,8 +19,8 @@ package org.springframework.boot.bind;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.LinkedHashMap;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
 
 import org.springframework.beans.MutablePropertyValues;
 import org.springframework.beans.PropertyValue;
@@ -42,7 +42,7 @@ import org.springframework.validation.DataBinder;
  */
 public class PropertySourcesPropertyValues implements PropertyValues {
 
-	private final Map<String, PropertyValue> propertyValues = new ConcurrentHashMap<String, PropertyValue>();
+	private final Map<String, PropertyValue> propertyValues = new LinkedHashMap<String, PropertyValue>();
 
 	private final PropertySources propertySources;
 

spring-boot/src/test/java/org/springframework/boot/bind/PropertySourcesPropertyValuesTests.java

@@ -16,11 +16,14 @@
 
 package org.springframework.boot.bind;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.LinkedHashMap;
 
 import org.junit.Before;
 import org.junit.Test;
+import org.springframework.beans.PropertyValue;
 import org.springframework.core.env.CompositePropertySource;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.MutablePropertySources;
@@ -61,6 +64,26 @@ public class PropertySourcesPropertyValuesTests {
 		assertEquals(1, propertyValues.getPropertyValues().length);
 	}
 
+	@Test
+	public void testOrderPreserved() {
+		LinkedHashMap<String, Object> map = new LinkedHashMap<String, Object>();
+		map.put("one", 1);
+		map.put("two", 2);
+		map.put("three", 3);
+		map.put("four", 4);
+		map.put("five", 5);
+		this.propertySources.addFirst(new MapPropertySource("ordered", map));
+		PropertySourcesPropertyValues propertyValues = new PropertySourcesPropertyValues(
+				this.propertySources);
+		PropertyValue[] values = propertyValues.getPropertyValues();
+		assertEquals(6, values.length);
+		Collection<String> names = new ArrayList<String>();
+		for (PropertyValue value : values) {
+			names.add(value.getName());
+		}
+		assertEquals("[one, two, three, four, five, name]", names.toString());
+	}
+
 	@Test
 	public void testNonEnumeratedValue() {
 		PropertySourcesPropertyValues propertyValues = new PropertySourcesPropertyValues(