If you check out all the sources from nuxeo.org, you need to do two things before building (big H/T to Stefane F. on this one):

  1. In the top-level (nuxeo) directory copy the build.properties.sample to build.properties and edit the file to point to your copy of jboss.  Use the forward slashes as shown in the sample. 
  2. Set the maven options to "-Xmx512M" and get rid of the -o that is in the sample, unless you are sure you want that and if you don't know why you want it, you probably don't.

The -Xmx512M sets the amount of heap allowed for the java process that runs maven itself, not necessarily the compilations that maven launches. Without this, you may find that builds are very slow or fail entirely by running out of resources. I have found that this makes my builds take about 20 minutes instead of about 50!