Maven is not working in Java 8 when Javadoc tags are incomplete

Question

Since I use Maven I have been able to build and install in my local repository projects that have incomplete Javadoc tags (for example, a missing parameter).

However, since I migrated to Java 8 (1.8.0-ea-b90) Maven is absolutely strict about missing documentation tags and show me lots of Javadoc errors related to Javadoc problems when I try to build or install a project where the Javadoc is not "perfect". Some of the projects I am trying to compile and install in my local repository are third party projects from which I do not have control. So the workaround of just fixing all the Javadocs in all these projects does not seem to be feasable in my scenario.

This is a small part of the output I see when I execute mvn clean package install in my project:

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 9.026s
[INFO] Finished at: Mon Apr 08 21:06:17 CEST 2013
[INFO] Final Memory: 27M/437M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:2.9:jar (attach-javadocs) on project jpc: MavenReportException: Error while creating archive:
[ERROR] Exit code: 1 - /Users/sergioc/Documents/workspaces/heal/jpc/src/main/java/org/jpc/engine/prolog/PrologDatabase.java:10: error: @param name not found
[ERROR] * @param terms the terms to assert
[ERROR] ^
[ERROR] /Users/sergioc/Documents/workspaces/heal/jpc/src/main/java/org/jpc/engine/prolog/PrologDatabase.java:11: warning: no description for @return
[ERROR] * @return
[ERROR] ^

The Javadoc Maven plugin is configured like this in my POM:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-javadoc-plugin</artifactId>
    <version>2.9</version>
    <executions>
        <execution>
            <id>attach-javadocs</id>
            <goals>
                <goal>jar</goal>
            </goals>
        </execution>
    </executions>
</plugin>

As I said before, everything is working fine if I go back to Java 7. Maybe is this a bug related to Maven running in Java 8? How could I make it work (i.e., being able to build the Javadoc of the project and install its code in my local repository) with Java 8? I have tested with both Maven 3.0.3 and 3.0.5 in OSX.

UPDATE:

If I change my Javadoc plugin configuration with <failOnError>false</failOnError> (thanks Martin):

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-javadoc-plugin</artifactId>
    <version>2.9</version>
    <executions>
        <execution>
            <id>attach-javadocs</id>
            <goals>
                <goal>jar</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Then the project is installed in my local repository. However, the Javadoc JAR is still not generated.

A fragment of the output I see in the console with this new configuration is:

[ERROR] MavenReportException: Error while creating archive: Exit code: 1 - /Users/....java:18: warning: no @param ... Command line was: /Library/Java/Home/bin/javadoc @options @packages

Refer to the generated Javadoc files in '/Users/sergioc/Documents/workspaces/heal/minitoolbox/target/apidocs' dir.

at org.apache.maven.plugin.javadoc.AbstractJavadocMojo.executeJavadocCommandLine(AbstractJavadocMojo.java:5043) at org.apache.maven.plugin.javadoc.AbstractJavadocMojo.executeReport(AbstractJavadocMojo.java:1990) at org.apache.maven.plugin.javadoc.JavadocJar.execute(JavadocJar.java:181) at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153) at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84) at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59) at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183) at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156) at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537) at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196) at org.apache.maven.cli.MavenCli.main(MavenCli.java:141) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:491) at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290) at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230) at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409) at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)

Any workaround about how to build the sources, install the project and generate the Javadoc JAR in one step as it was working with Java 7?

Answer 1

The best solution would be to fix the javadoc errors. If for some reason that is not possible (ie: auto generated source code) then you can disable this check.

DocLint is a new feature in Java 8, which is summarized as:

Provide a means to detect errors in Javadoc comments early in the development cycle and in a way that is easily linked back to the source code.

This is enabled by default, and will run a whole lot of checks before generating Javadocs. You need to turn this off for Java 8 as specified in this thread. You'll have to add this to your maven configuration:

<profiles>
  <profile>
    <id>java8-doclint-disabled</id>
    <activation>
      <jdk>[1.8,)</jdk>
    </activation>
    <properties>
      <javadoc.opts>-Xdoclint:none</javadoc.opts>
    </properties>
  </profile>
</profiles>
<build>
  <plugins>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-javadoc-plugin</artifactId>
        <version>2.9</version>
        <executions>
            <execution>
                <id>attach-javadocs</id>
                <goals>
                    <goal>jar</goal>
                </goals>
                <configuration>
                    <additionalparam>${javadoc.opts}</additionalparam>
                </configuration>
            </execution>
        </executions>
    </plugin>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-site-plugin</artifactId>
        <version>3.3</version>
        <configuration>
          <reportPlugins>
            <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-javadoc-plugin</artifactId>
              <configuration>
                <additionalparam>${javadoc.opts}</additionalparam>
              </configuration>
            </plugin>
          </reportPlugins>
        </configuration>
      </plugin>
   </plugins>
</build>

For maven-javadoc-plugin 3.0.0+: Replace

<additionalparam>-Xdoclint:none</additionalparam>

with

<doclint>none</doclint>

Answer 2

The easiest approach to get things working with both java 8 and java 7 is to use a profile in the build:

<profiles>
  <profile>
    <id>doclint-java8-disable</id>
    <activation>
      <jdk>[1.8,)</jdk>
    </activation>

    <build>
      <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-javadoc-plugin</artifactId>
          <configuration>
            <additionalparam>-Xdoclint:none</additionalparam>
          </configuration>
        </plugin>
      </plugins>
    </build>
  </profile>
</profiles>