Add a second, portal-compatible ID to the Gradle plugin

To be compatible with Gradle's plugin portal, plugins must have an
ID that uses a reverse domain name. This means that spring-boot is
not compatible.

This commit introduces a new ID, org.springframework.boot, and
deprecates the old ID.

Closes gh-6997

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

@@ -34,7 +34,7 @@ import org.springframework.boot.loader.tools.Layouts;
  * two of them. E.g.
  *
  * <pre>
- *     apply plugin: "spring-boot"
+ *     apply plugin: 'org.springframework.boot'
  *     springBoot {
  *         mainClass = 'org.demo.Application'
  *         layout = 'ZIP'

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

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2016 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.boot.gradle.plugin;
+
+import org.gradle.api.Project;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * {@link SpringBootPlugin} subclass that outputs a deprecation warning to direct people
+ * to use the new Gradle Plugin Portal-compatible ID {@code org.springframework.boot}.
+ *
+ * @author Andy Wilkinson
+ * @deprecated since 1.4.2 in favor of {@link SpringBootPlugin}
+ */
+@Deprecated
+public class DeprecatedSpringBootPlugin extends SpringBootPlugin {
+
+	private static final Logger logger = LoggerFactory
+			.getLogger(DeprecatedSpringBootPlugin.class);
+
+	@Override
+	public void apply(Project project) {
+		logger.warn("The plugin id 'spring-boot' is deprecated. Please use "
+				+ "'org.springframework.boot' instead.");
+		super.apply(project);
+	}
+
+}

spring-boot-tools/spring-boot-gradle-plugin/src/main/resources/META-INF/gradle-plugins/org.springframework.boot.properties

@@ -0,0 +1 @@
+implementation-class=org.springframework.boot.gradle.plugin.SpringBootPlugin

spring-boot-tools/spring-boot-gradle-plugin/src/main/resources/META-INF/gradle-plugins/spring-boot.properties

@@ -1 +1 @@
-implementation-class=org.springframework.boot.gradle.plugin.SpringBootPlugin
+implementation-class=org.springframework.boot.gradle.plugin.DeprecatedSpringBootPlugin