Make sure bootstrap sources are ordered before use.

Make call to sort() before setting on builder.sources().

fixes gh-176

(cherry picked from commit 6dc35d1)

spring-cloud-context/src/test/java/org/springframework/cloud/bootstrap/BootstrapSourcesOrderingTests.java

@@ -0,0 +1,34 @@
+package org.springframework.cloud.bootstrap;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.bootstrap.BootstrapOrderingSpringApplicationJsonIntegrationTests.Application;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.bootstrap.TestHigherPriorityBootstrapConfiguration.firstToBeCreated;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = Application.class)
+public class BootstrapSourcesOrderingTests {
+
+	@Autowired
+	private ConfigurableEnvironment environment;
+
+	@Test
+	public void sourcesAreOrderedCorrectly() {
+		Class<?> firstConstructedClass = firstToBeCreated.get();
+		assertThat(firstConstructedClass).as("bootstrap sources not ordered correctly").isEqualTo(TestHigherPriorityBootstrapConfiguration.class);
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	protected static class Application {
+	}
+
+}

spring-cloud-context/src/test/java/org/springframework/cloud/bootstrap/TestBootstrapConfiguration.java

@@ -0,0 +1,17 @@
+package org.springframework.cloud.bootstrap;
+
+import org.springframework.core.annotation.Order;
+
+import static org.springframework.cloud.bootstrap.TestHigherPriorityBootstrapConfiguration.firstToBeCreated;
+
+/**
+ * @author Spencer Gibb
+ */
+@Order(0)
+public class TestBootstrapConfiguration {
+
+	public TestBootstrapConfiguration() {
+		firstToBeCreated.compareAndSet(null, TestBootstrapConfiguration.class);
+	}
+
+}

spring-cloud-context/src/test/java/org/springframework/cloud/bootstrap/TestHigherPriorityBootstrapConfiguration.java

@@ -0,0 +1,20 @@
+package org.springframework.cloud.bootstrap;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
+
+/**
+ * @author Spencer Gibb
+ */
+@Order(Ordered.HIGHEST_PRECEDENCE)
+public class TestHigherPriorityBootstrapConfiguration {
+
+	static final AtomicReference<Class<?>> firstToBeCreated = new AtomicReference<>();
+
+	public TestHigherPriorityBootstrapConfiguration() {
+		firstToBeCreated.compareAndSet(null, TestHigherPriorityBootstrapConfiguration.class);
+	}
+
+}