First thing I see is this:
Where is that defined in your script? It looks like you are expecting the environment containing that value to be passed into the script ... but that does not happen with cron jobs.
The easiest thing to do is to define JBOSS_HOME in the script ... the second thing to do if you are adventurous is to try placing the -l (dash el) option to the she-bang line of your script:
The -l will cause the script to import the environment of the user executing the script ... SO ... you have to make sure the user executing the script has JBOSS_HOME defined someplace (likely in /etc/profile.d/, or the user's home directory .bashrc, etc).