change a ! -z to a -n for clarity
change a ! -z to a -n for clarity

noncreativetype/sms,Parlio/heroku-buildpack-java,Vincit/heroku-buildpack-java-nodejs,noncreativetype/sms,noncreativetype/sms,neilgandhi/heroku-buildpack-java,wishtack/heroku-buildpack-java,RaymondKroon/heroku-buildpack-vertx,heroku/heroku-buildpack-java,JIoJIaJIu/heroku-buildpack-java,kimonocloud/natsu-buildpack-java,JIoJIaJIu/heroku-buildpack-java,bluebreezecf/heroku-buildpack-java,hpcloud/heroku-buildpack-java,Scalingo/java-buildpack,kimonocloud/natsu-buildpack-java,bluebreezecf/heroku-buildpack-java,Parlio/heroku-buildpack-java,franciscocpg/heroku-buildpack-java,wishtack/heroku-buildpack-java,neilgandhi/heroku-buildpack-java,Vincit/heroku-buildpack-java-nodejs,heroku/heroku-buildpack-java,franciscocpg/heroku-buildpack-java,hpcloud/heroku-buildpack-java,Scalingo/java-buildpack,RaymondKroon/heroku-buildpack-vertx