Referencing resources directory from project object model variables
${project.build.resources[0].directory}
maven reference @ Sonatype, chapter 'resource filtering' says that anything from maven internal "Model.class" can be accessed. quote :
"For a full list of properties available on the Maven Model object, take a look at the JavaDoc for the maven-model project here http://maven.apache.org/ref/3.0.4/maven-model/apidocs/index.html. Once you load this JavaDoc, take a look at the Model class. From this Model class JavaDoc, you should be able to navigate to the POM property you wish to reference."
Then, maven help plugin has a handy help:evaluate goal that let you do trial&error to discover the properties.
From here:
directory: This element's value defines where the resources are to be found. The default directory for a build is
${basedir}/src/main/resources
.
Edit: for clarity