Allow default DevTools properties to be overridden

Previously the default DevTools property source was added in first place
to the environment’s property sources in an unordered environment
post-processor. This made it difficult to override them.

This commit updates the post-processor to be ordered with lowest
precedence and to add the property source in last place. This should
allow any other property sources and to override the defaults.

Closes gh-3851

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/env/DevToolsPropertyDefaultsPostProcessor.java

@@ -22,6 +22,8 @@ import java.util.Map;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.env.EnvironmentPostProcessor;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.PropertySource;
@@ -34,6 +36,7 @@ import org.springframework.core.env.PropertySource;
  * @author Andy Wilkinson
  * @since 1.3.0
  */
+@Order(Ordered.LOWEST_PRECEDENCE)
 public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostProcessor {
 
 	private static final Map<String, Object> PROPERTIES;
@@ -56,7 +59,7 @@ public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostPro
 		if (isLocalApplication(environment)) {
 			PropertySource<?> propertySource = new MapPropertySource("refresh",
 					PROPERTIES);
-			environment.getPropertySources().addFirst(propertySource);
+			environment.getPropertySources().addLast(propertySource);
 		}
 	}
 

spring-boot-devtools/src/test/java/org/springframework/boot/devtools/autoconfigure/LocalDevToolsAutoConfigurationTests.java

@@ -90,6 +90,30 @@ public class LocalDevToolsAutoConfigurationTests {
 		assertThat(resolver.isCacheable(), equalTo(false));
 	}
 
+	@Test
+	public void defaultPropertyCanBeOverridenFromCommandLine() throws Exception {
+		this.context = initializeAndRun(Config.class, "--spring.thymeleaf.cache=true");
+		TemplateResolver resolver = this.context.getBean(TemplateResolver.class);
+		resolver.initialize();
+		assertThat(resolver.isCacheable(), equalTo(true));
+	}
+
+	@Test
+	public void defaultPropertyCanBeOverridenFromUserHomeProperties() throws Exception {
+		String userHome = System.getProperty("user.home");
+		System.setProperty("user.home",
+				new File("src/test/resources/user-home").getAbsolutePath());
+		try {
+			this.context = initializeAndRun(Config.class);
+			TemplateResolver resolver = this.context.getBean(TemplateResolver.class);
+			resolver.initialize();
+			assertThat(resolver.isCacheable(), equalTo(true));
+		}
+		finally {
+			System.setProperty("user.home", userHome);
+		}
+	}
+
 	@Test
 	public void resourceCachePeriodIsZero() throws Exception {
 		this.context = initializeAndRun(WebResourcesConfig.class);
@@ -210,17 +234,18 @@ public class LocalDevToolsAutoConfigurationTests {
 		assertThat(folders, hasKey(new File("src/test/java").getAbsoluteFile()));
 	}
 
-	private ConfigurableApplicationContext initializeAndRun(Class<?> config) {
-		return initializeAndRun(config, Collections.<String, Object>emptyMap());
+	private ConfigurableApplicationContext initializeAndRun(Class<?> config,
+			String... args) {
+		return initializeAndRun(config, Collections.<String, Object>emptyMap(), args);
 	}
 
 	private ConfigurableApplicationContext initializeAndRun(Class<?> config,
-			Map<String, Object> properties) {
+			Map<String, Object> properties, String... args) {
 		Restarter.initialize(new String[0], false, new MockRestartInitializer(), false);
 		SpringApplication application = new SpringApplication(config);
 		application.setDefaultProperties(getDefaultProperties(properties));
 		application.setWebEnvironment(false);
-		ConfigurableApplicationContext context = application.run();
+		ConfigurableApplicationContext context = application.run(args);
 		return context;
 	}