Glitch php skeleton and function exec()

Hello, i have cloned this skeleton for php on github GitHub - dragonmantank/glitch-php-skeleton: This is a quick setup for using PHP on and the php code work fine.
But when the conde launch a java jar file with the php function exec() it dont work. I try to set the full path of java command and of a file jar without result. From terminal if i type the command java the application respond. Can someone help me? Thanks in advaces