Javadoc generation does not work with Java 9

[snicoll]

Executing

$ mvn clean install -U -DskipTests -Pfull -s ../settings.xml

From the spring-boot-full-build directory yield:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:3.0.0-M1:jar (attach-javadocs) on project spring-boot-devtools: MavenReportException: Error while generating Javadoc:
[ERROR] Exit code: 1 - /Users/snicoll/workspace/pivotal/spring-boot/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/HateoasObjenesisCacheDisabler.java:21: error: package javax.annotation is not visible
[ERROR] import javax.annotation.PostConstruct;
[ERROR]             ^
[ERROR]   (package javax.annotation is declared in module java.xml.ws.annotation, which is not in the module graph)
[ERROR] /Users/snicoll/workspace/pivotal/spring-boot/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/OptionalLiveReloadServer.java:19: error: package javax.annotation is not visible
[ERROR] import javax.annotation.PostConstruct;
[ERROR]             ^
[ERROR]   (package javax.annotation is declared in module java.xml.ws.annotation, which is not in the module graph)
[ERROR] /Users/snicoll/workspace/pivotal/spring-boot/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/remote/client/RemoteClientConfiguration.java:27: error: package javax.annotation is not visible
[ERROR] import javax.annotation.PostConstruct;
[ERROR]             ^
[ERROR]   (package javax.annotation is declared in module java.xml.ws.annotation, which is not in the module graph)
[ERROR]

(You need to upgrade to maven-javadoc-plugin 3.0.0+ first)

[wilkinsona]

We have dependency management for the Annotation API jar now so this can be resolved with these changes:

diff --git a/spring-boot-dependencies/pom.xml b/spring-boot-dependencies/pom.xml
index 37762f8bac..266fa49462 100644
--- a/spring-boot-dependencies/pom.xml
+++ b/spring-boot-dependencies/pom.xml
@@ -217,7 +217,7 @@
                <maven-invoker-plugin.version>3.0.0</maven-invoker-plugin.version>
                <maven-help-plugin.version>2.2</maven-help-plugin.version>
                <maven-jar-plugin.version>3.0.2</maven-jar-plugin.version>
-               <maven-javadoc-plugin.version>2.10.4</maven-javadoc-plugin.version>
+               <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
                <maven-resources-plugin.version>3.0.1</maven-resources-plugin.version>
                <maven-shade-plugin.version>2.4.3</maven-shade-plugin.version>
                <maven-site-plugin.version>3.5.1</maven-site-plugin.version>
diff --git a/spring-boot-devtools/pom.xml b/spring-boot-devtools/pom.xml
index 559a2470a3..53602046e4 100644
--- a/spring-boot-devtools/pom.xml
+++ b/spring-boot-devtools/pom.xml
@@ -85,6 +85,12 @@
                        <artifactId>spring-boot-configuration-processor</artifactId>
                        <optional>true</optional>
                </dependency>
+               <!-- Provided (Javadoc on Java 9) -->
+               <dependency>
+                       <groupId>javax.annotation</groupId>
+                       <artifactId>javax.annotation-api</artifactId>
+                       <scope>provided</scope>
+               </dependency>
                <!-- Test -->
                <dependency>
                        <groupId>org.springframework.boot</groupId>

DevTools has a compile and runtime dependency on javax.annotation.PostConstruct. That class is provided by the JDK on Java 8, but not on Java 9. Anyone using spring-boot-starter now also has javax.annotation:javax.annotation-api on the classpath so DevTools expecting it to be provided doesn't feel unreasonable to me. Thoughts?

[philwebb]

Seems reasonable to me. We might also be able to refactor DevTools to use InitializingBean instead.