Maintain classpath order in PropertiesLauncher

I think this is safe, judging by the integration tests, but I'm not
putting it in 1.2.x until we've had some feedback on it. The
integration tests actually had a bug that was masking this problem
because they were merging Properties from the whole classpath instead
of picking the first available resource (which is generally what
we do in Spring Boot applications for application.properties for
instance).

Fixes gh-3048

spring-boot-docs/src/main/asciidoc/appendix-executable-jar-format.adoc

@@ -202,7 +202,7 @@ properties (System properties, environment variables, manifest entries or
 |Key |Purpose
 
 |`loader.path`
-|Comma-separated Classpath, e.g. `lib:${HOME}/app/lib`.
+|Comma-separated Classpath, e.g. `lib,${HOME}/app/lib`. Earlier entries take precedence, just like a regular `-classpath` on the `javac` command line.
 
 |`loader.home`
 |Location of additional properties file, e.g. `file:///opt/app`
@@ -236,6 +236,7 @@ Environment variables can be capitalized with underscore separators instead of p
   the default) as long as `loader.config.location` is   not specified.
 * `loader.path` can contain directories (scanned recursively for jar and zip files),
   archive paths, or wildcard patterns (for the default JVM behavior).
+* `loader.path` (if empty) defaults to `lib` (meaning a local directory or a nested one if running from an archive). Because of this `PropertiesLauncher` behaves the same as `JarLauncher` when no additional configuration is provided.
 * Placeholder replacement is done from System and environment variables plus the
   properties file itself on all values before use.
 

spring-boot-tools/spring-boot-loader/src/it/executable-props/src/main/java/org/springframework/launcher/it/props/SpringConfiguration.java

@@ -17,12 +17,13 @@
 package org.springframework.boot.load.it.props;
 
 import java.io.IOException;
+import java.util.Properties;
 
 import javax.annotation.PostConstruct;
 
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.core.io.support.PropertiesLoaderUtils;
+import org.springframework.core.io.ClassPathResource;
 
 /**
  * Spring configuration.
@@ -37,7 +38,9 @@ public class SpringConfiguration {
 
 	@PostConstruct
 	public void init() throws IOException {
-		String value = PropertiesLoaderUtils.loadAllProperties("application.properties").getProperty("message");
+		Properties props = new Properties();
+		props.load(new ClassPathResource("application.properties").getInputStream());
+		String value = props.getProperty("message");
 		if (value!=null) {
 			this.message = value;
 		}

spring-boot-tools/spring-boot-loader/src/it/executable-props/verify.groovy

@@ -26,7 +26,6 @@ assert out.contains('Hello Embedded Foo!'),
 	'With loader.path=.,lib should use the application.properties from the local filesystem\n' + out
 
 new File("${basedir}/target/application.properties").withWriter { it -> it << "message: Spam" }
-
 out = exec("java -Dloader.path=target,.,lib -jar ${jarfile}")
 assert out.contains('Hello Embedded Spam!'),
 	'With loader.path=target,.,lib should use the application.properties from the target directory\n' + out
\ No newline at end of file

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/Launcher.java

@@ -75,8 +75,6 @@ public abstract class Launcher {
 	protected ClassLoader createClassLoader(List<Archive> archives) throws Exception {
 		List<URL> urls = new ArrayList<URL>(archives.size());
 		for (Archive archive : archives) {
-			// Add the current archive at end (it will be reversed and end up taking
-			// precedence)
 			urls.add(archive.getUrl());
 		}
 		return createClassLoader(urls.toArray(new URL[urls.size()]));

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/PropertiesLauncher.java

@@ -448,8 +448,6 @@ public class PropertiesLauncher extends Launcher {
 			}
 		}
 		addParentClassLoaderEntries(lib);
-		// Entries are reversed when added to the actual classpath
-		Collections.reverse(lib);
 		return lib;
 	}
 

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/PropertiesLauncherTests.java

@@ -134,6 +134,17 @@ public class PropertiesLauncherTests {
 		waitFor("Hello World");
 	}
 
+	@Test
+	public void testUserSpecifiedClassPathOrder() throws Exception {
+		System.setProperty("loader.path", "more-jars/app.jar,jars/app.jar");
+		System.setProperty("loader.classLoader", URLClassLoader.class.getName());
+		PropertiesLauncher launcher = new PropertiesLauncher();
+		assertEquals("[more-jars/app.jar, jars/app.jar]",
+				ReflectionTestUtils.getField(launcher, "paths").toString());
+		launcher.launch(new String[0]);
+		waitFor("Hello Other World");
+	}
+
 	@Test
 	public void testCustomClassLoaderCreation() throws Exception {
 		System.setProperty("loader.classLoader", TestLoader.class.getName());