Maven plugins using Javadoc MOJO descriptors FTBFS

[Pushkar Kulkarni]

The build in -proposed failed [1] on plucky because maven cannot find the Javadoc-based Mojo descriptions. The same package builds successfully in Debian unstable (which has the same versions of the build-deps).

The reason for the failure is that the Javadoc Mojo Descriptor extractor is not loaded in the failing environment. I have done some investigation but have yet not found answers to why the Javadoc extractor is missing. There is no evidence for this in the plugin configuration.

The gettext-maven-plugin is affected by the same problem [2].

[1] https://launchpadlibrarian.net/759073948/buildlog_ubuntu-plucky-amd64.antlr-maven-plugin_2.2-7_BUILDING.txt.gz

[2] https://launchpadlibrarian.net/759073901/buildlog_ubuntu-plucky-amd64.gettext-maven-plugin_1.2.9-5_BUILDING.txt.gz

[Pushkar Kulkarni (pushkarnk)]

Here is a synopsis of the failure investigation.

Packages antlr-maven-plugin and gettext-maven-plugins are maven plugins that use the Javadoc-based Mojo descriptor. That Javadoc MOJO descriptor, along with Ant-based and Beanshell-based MOJO descriptors, is deprecated. Support for these descriptors will be removed in Maven 4.

MOJO descriptor extractor classes are included in package maven-plugin-tools. The antlr-maven-plugin and gettext-maven-plugins packages FTBFS because b-d maven-plugin-tools 3.10.2-1 (which must support Javadoc Mojos) fails to discover the JavaJavadocMojoDescriptorExtractor class present in maven-plugin-tools-java-debian.jar.

The extractor classes are discovered and instantiated and into the maven workflow through dependency injection, by the sisu-maven-plugin [1]. For the latter to discover these classes, they need to be indexed in a file named "META-INF/sisu/javax.inject.Named" [2] packaged in the maven-plugin-tools-java-debian.jar. However, this file isn't found in that JAR file shipped with libmaven-plugin-tools-java, the binary package for maven-plugin-tools.

The current binaries of libmaven-plugin-tools-java on Debian unstable do include the index file. I don't have an explanation for that. But when I tried to build the maven-plugin-tools source package in Debian sid, I could not find the index file.

There are no changes between maven-plugin-tools 3.7.1-1 and 3.10.2-1 which would suggest why the index file was packaged in 3.7.1-1, but is not included in 3.10.2-1. I cannot explain how it got included in 3.7.1-1! I know why it doesn't exist in 3.10.2-1.

Similar index files are found in the maven-plugin-tools-ant-debian.jar and maven-plugin-tools-beanshell-debian.jar which also ship with libmaven-plugin-tools-java.

A short-term solution, for now, is to make sure the index file gets added to the maven-plugin-tools-java-debian.jar on Ubuntu. The patch would be irrelevant once Maven 4 is released.

[1] https://launchpad.net/ubuntu/+source/sisu-mojos
[2] https://maven.apache.org/maven-jsr330.html