Maven dependency bug can lead to very confusing failures

The purpose of this report is to suggest an FAQ entry or other web content, as follows.

Using the Maven Antrun Plugin in multiple projects in the Reactor

In Maven 2.0.x, there is a significant bug that can lead to very perplexing failures with the antrun plugin. There are two conditions that you have to meet to get into this problem.

1) You have to use the plugin in two projects that are loaded into the reactor via <modules/> .
2) You have to require additional plugin dependencies on the plugin.

In Maven 2.0.x, the dependencies of the first project into the reactor win, and all the others are entirely ignored.

Concretely, if your first project uses the plugin with no special dependencies, and your second one tries to use ant-trax, the second antrun execution will fail, and complain that it can't find the classes in ant-trax.

The only solution to this is to ensure that, in all of the places where you use the plugin, you list the same dependencies.