Unable to get module properties

<sources>
.....
<outputDirectoryMapping>${module.properties.foo}</outputDirectoryMapping>
.....
</sources>

doesn't return me the property "foo" which should be in the corresponding POM file. The property is defined correctly. Following works:
-module.properties (I get a long string, and I can see "foo=bar")
-project.properties.foo (where I also explicitly defined the property in POM)