Churchill Nolan Churchill Nolan - 1 year ago 79
Java Question

How to use MavenBuildHelper in Maven mojo

I am developing a maven-plugin with multiple Mojos. In one of them, my goal is to attach additional artifact to my project. Similar to attach-artifact of maven-build-helper-plugin. But I don't want to use any given build plugin, I want to do it through my Mojo.

I know that I have to use MavenProjectHelper.attachArtifact. Because MavenProject.attachArtifact is deprecated.

What I have now is this (in the

@Parameter(defaultValue = "${project}", required = true, readonly = true)
private MavenProject project;

@Parameter(defaultValue = "${helper}", required = true, readonly = true)
protected MavenProjectHelper projectHelper;

And in

projectHelper.attachArtifact(project, "plugin", file);

But the problem is,
's default value is not
. Which is why, I get the following error:

Failed to execute goal (default) on project consumer-plugin: The parameters 'projectHelper' for goal are missing or invalid -> [Help 1]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1]

How do I give it the correct value? Like
, I have assumed that
has a default value. If so, what is it? If not, then how can I give the correct value to

Answer Source

The MavenProjectHelper is a Plexus component, not a plugin parameter, and should be injected by annotating it with the @org.apache.maven.plugins.annotations.Component annotation:

Used to configure injection of Plexus components by MavenPluginManager.getConfiguredMojo(...).

Thus, you should have instead:

private MavenProjectHelper projectHelper;

This annotation, just like @Parameter, comes with the Plugin Tools for annotations, that you can declare in the POM of your Maven plugin with


To clarify further, what you can inject with @Parameter is documented in the Javadoc of the PluginParameterExpressionEvaluator class (among others, session for the Maven session, project for the current Maven project or mojoExecution for the current Mojo execution).