Release Of A Maven-Plugin to Maven Central Fails With “error: unknown tag: goal”

error: unknown tag: goal

Releasing a maven-plugin via Maven Central does not work, if you have switched to Java 8. This happens, because hidden in the oss-parent, that you have to configure as parent of your project to be able to release it via Sonatype, the maven-javadoc-plugin is configured for you. And the version of javadoc, that is shipped with Java 8, by default checks the syntax of the comments and fails, if anything unexpected is seen.

Unfortunatly, the special javadoc-tag’s, like @goal or @phase, that are needed to configure the maven-plugin, are unexpected for javadoc.

Solution 1: Turn Of The Linting Again

As described elswehere, you can easily turn of the linting in the plugins-section of your pom.xml:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-javadoc-plugin</artifactId>
  <version>2.7</version>
  <configuration>
    <additionalparam>-Xdoclint:none</additionalparam>
  </configuration>
</plugin>

Solution 2: Tell javadoc About The Unknown Tags

Another not so well known approach, that I found in a fix for an issue of some project, is, to add the unknown tag’s in the configuration of the maven-javadoc-plugin:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-javadoc-plugin</artifactId>
  <version>2.7</version>
  <configuration>
    <tags>
      <tag>
        <name>goal</name>
        <placement>a</placement>
        <head>Goal:</head>
      </tag>
      <tag>
        <name>phase</name>
        <placement>a</placement>
        <head>Phase:</head>
      </tag>
      <tag>
        <name>threadSafe</name>
        <placement>a</placement>
        <head>Thread Safe:</head>
      </tag>
      <tag>
        <name>requiresDependencyResolution</name>
        <placement>a</placement>
        <head>Requires Dependency Resolution:</head>
      </tag>
      <tag>
        <name>requiresProject</name>
        <placement>a</placement>
        <head>Requires Project:</head>
      </tag>
    </tags>
  </configuration>
</plugin>

Funded by the Europian Union

This article was published in the course of a resarch-project, that is funded by the European Union and the federal state Northrhine-Wetphalia.

Europäische Union: Investitionen in unsere Zukunft - Europäischer Fonds für regionale Entwicklung EFRE.NRW 2014-2020: Invesitionen in Wachstum und Beschäftigung

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