The maven-properties-plugin sources used to be hosted on Codehaus (http://mojo.codehaus.org/properties-maven-plugin), but I cannot find the new home for the sources anywhere.
Does anyone know if they have been migrated somewhere? I checked the CodeHaus github repository, but can't find them there.
The last known version was 1.0-alpha2.
The codehaus project has been moved to another location at www.mojohaus.org, they also have a GitHub home page at: https://github.com/mojohaus/.
The sources your are looking for is at https://github.com/mojohaus/properties-maven-plugin