Setting the license property is an effective way to override the "Default License", but this feature is not promoted.  I suggest adding an example of the property setting to the User.properties file.  

Here is a suggested example for the default User.properties file:

#
# Here, or in other properties files in this directory, you can define 
# various properties that you want to make available to the template
# processor while creating various templates.

# uncomment the next line and specify your user name to be used in new templates
#user=Your Name <your.name at your.org>

# uncomment one of the license templates to be used for new source files.
#license=apache20
#license=bsd3
#license=cddl-netbeans-sun
#license=default
#license=epl10
#license=gpl20
#license=gpl30
#license=lgpl21