Rework @PropertySource early parsing logic

Rework the @PropertySource parsing logic recently changed in commit
7c608886 to deal with the same source appearing on a @Configuration
class and an @Import class.

Processing now occurs in a single sweep, with any previously added
sources being converted to a CompositePropertySource.

Issue: SPR-12115

spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java

@@ -16,7 +16,9 @@
 
 package org.springframework.core.env;
 
+import java.util.ArrayList;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Set;
 
 /**
@@ -25,6 +27,7 @@ import java.util.Set;
  * share the same name, e.g. when multiple values are supplied to {@code @PropertySource}.
  *
  * @author Chris Beams
+ * @author Phillip Webb
  * @since 3.1.1
  */
 public class CompositePropertySource extends PropertySource<Object> {
@@ -56,6 +59,13 @@ public class CompositePropertySource extends PropertySource<Object> {
 		this.propertySources.add(propertySource);
 	}
 
+	public void addFirstPropertySource(PropertySource<?> propertySource) {
+		List<PropertySource<?>> exisiting = new ArrayList<PropertySource<?>>(this.propertySources);
+		this.propertySources.clear();
+		this.propertySources.add(propertySource);
+		this.propertySources.addAll(exisiting);
+	}
+
 	@Override
 	public String toString() {
 		return String.format("%s [name='%s', propertySources=%s]",

spring-core/src/main/java/org/springframework/core/io/support/ResourcePropertySource.java

@@ -115,7 +115,7 @@ public class ResourcePropertySource extends PropertiesPropertySource {
 		this(new DefaultResourceLoader().getResource(location));
 	}
 
-	private ResourcePropertySource(String name, Map<String, Object> source) {
+	protected ResourcePropertySource(String name, Map<String, Object> source) {
 		super(name, source);
 	}
 
@@ -137,7 +137,7 @@ public class ResourcePropertySource extends PropertiesPropertySource {
 	 * empty, return the class name of the resource plus its identity hash code.
 	 * @see org.springframework.core.io.Resource#getDescription()
 	 */
-	private static String getNameForResource(Resource resource) {
+	protected static String getNameForResource(Resource resource) {
 		String name = resource.getDescription();
 		if (!StringUtils.hasText(name)) {
 			name = resource.getClass().getSimpleName() + "@" + System.identityHashCode(resource);

spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2002-2014 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.core.env;
+
+import java.util.Collections;
+
+import org.junit.Test;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+
+/**
+ * Tests for {@link CompositePropertySource}.
+ * @author Phillip Webb
+ */
+public class CompositePropertySourceTests {
+
+	@Test
+	public void addFirst() {
+		PropertySource<?> p1 = new MapPropertySource("p1", Collections.emptyMap());
+		PropertySource<?> p2 = new MapPropertySource("p2", Collections.emptyMap());
+		PropertySource<?> p3 = new MapPropertySource("p3", Collections.emptyMap());
+		CompositePropertySource composite = new CompositePropertySource("c");
+		composite.addPropertySource(p2);
+		composite.addPropertySource(p3);
+		composite.addPropertySource(p1);
+		composite.addFirstPropertySource(p1);
+		assertThat(composite.toString(), containsString("MapPropertySource [name='p1'], "
+				+ "MapPropertySource [name='p2'], MapPropertySource [name='p3']"));
+	}
+
+}