A common Maven debugging technique is to use mvn dependency:tree to view the graph of project dependencies.
However, this list shows the project dependencies, not
The output via mvn -X will printout the information indirectly. Currently there is no other option to get the dependencies of a Maven-Plugin.
Update You can use the following command to get a list of plugin dependencies (resolve-plugin goal from dependencies plugin):
mvn org.apache.maven.plugins:maven-dependency-plugin:2.10:resolve-plugins
The shorter version is (and it is a bad habit to specify plugin versions)
mvn dependency:resolve-plugins