How to add configurations in core-site.xml when install a new service?

[Zhang Ruiqiang]

Hi all:
      When install Oozie service, new configurations such as 
'hadoop.proxyuser.oozie.groups' will be added to core-site.xml. Now, I want to 
add similar configurations(''hadoop.proxyuser.XXX.groups') when I install a 
customed service. I checked the code, but I can't find out how to do this.
      Can anyone help me?


Regards!