Deprecate support for Gradle 2.7 and earlier

Author: wilkinsona

spring-boot-docs/src/main/asciidoc/getting-started.adoc

@@ -39,8 +39,8 @@ diverge from the defaults.
 By default, Spring Boot {spring-boot-version} requires http://www.java.com[Java 7] and
 Spring Framework {spring-version} or above. You can use Spring Boot with Java 6 with some
 additional configuration. See <<howto.adoc#howto-use-java-6>> for more details. Explicit
-build support is provided for Maven (3.2+) and Gradle (1.12 or 2.x). Gradle 3 is not
-supported.
+build support is provided for Maven (3.2+) and Gradle (1.12 or 2.x). Support for Gradle
+2.7 and earlier is deprecated. Gradle 3 is not supported.
 
 TIP: Although you can use Spring Boot with Java 6 or 7, we generally recommend Java 8 if
 at all possible.
@@ -205,9 +205,9 @@ scope.
 
 [[getting-started-gradle-installation]]
 ==== Gradle installation
-Spring Boot is compatible with Gradle 1.12 or 2.x. 2.14.1 is recommended. Gradle 3 is not
-supported. If you don't already have Gradle installed you can follow the instructions at
-http://www.gradle.org/.
+Spring Boot is compatible with Gradle 1.12 or 2.x but support for 2.7 and earlier is
+deprecated. Gradle 2.14.1 is recommended. Gradle 3 is not supported. If you don't already
+have Gradle installed you can follow the instructions at http://www.gradle.org/.
 
 Spring Boot dependencies can be declared using the `org.springframework.boot` `group`.
 Typically your project will declare dependencies to one or more

spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/plugin/SpringBootPlugin.java

@@ -22,6 +22,9 @@
 import org.gradle.api.Task;
 import org.gradle.api.plugins.JavaPlugin;
 import org.gradle.api.tasks.compile.JavaCompile;
+import org.gradle.util.GradleVersion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import org.springframework.boot.gradle.SpringBootPluginExtension;
 import org.springframework.boot.gradle.agent.AgentPluginFeatures;
@@ -38,8 +41,15 @@
  */
 public class SpringBootPlugin implements Plugin<Project> {
 
+	private static final Logger logger = LoggerFactory.getLogger(SpringBootPlugin.class);
+
 	@Override
 	public void apply(Project project) {
+		if (GradleVersion.current().compareTo(GradleVersion.version("2.8")) < 0) {
+			logger.warn("Spring Boot plugin's support for Gradle "
+					+ GradleVersion.current().getVersion()
+					+ " is deprecated. Please upgrade to Gradle 2.8 or later.");
+		}
 		project.getExtensions().create("springBoot", SpringBootPluginExtension.class,
 				project);
 		project.getPlugins().apply(JavaPlugin.class);