KnoxLine NPE list datasources when directories don't exist

| | ___ __ _____ _| (_)_ __ ___ 
| |/ / '_ \ / _ \ \/ / | | '_ \ / _ \
| <| | | | (_) > <| | | | | | __/
|_|\_\_| |_|\___/_/\_\_|_|_| |_|\\__|
powered by Apache Knox


knoxline> :ds
java.lang.NullPointerException
 at org.apache.knox.gateway.shell.jdbc.KnoxLine.listDataSources(KnoxLine.java:135)
 at org.apache.knox.gateway.shell.jdbc.KnoxLine.processDataSourceCommand(KnoxLine.java:110)
 at org.apache.knox.gateway.shell.jdbc.KnoxLine.executeShell(KnoxLine.java:71)
 at org.apache.knox.gateway.shell.jdbc.KnoxLine.execute(KnoxLine.java:51)
 at org.apache.knox.gateway.shell.KnoxSh$KnoxLineCommand.execute(KnoxSh.java:412)
 at org.apache.knox.gateway.shell.KnoxSh.run(KnoxSh.java:88)
 at org.apache.knox.gateway.shell.KnoxSh.main(KnoxSh.java:427)
 at org.apache.knox.gateway.shell.Shell.main(Shell.java:74)
Closing any open connections ...