mutect-1.1.7 stack error

I was looking at this post because it appeared to have the same problem that I am having http://gatkforums.broadinstitute.org/gatk/discussion/6054/stack-error-when-run-mutect-the-first-time ; however, the fix that was mentioned is to download mutect-1.1.7, which I am currently using and gives me this same error.

ERROR ------------------------------------------------------------------------------------------

ERROR stack trace

java.lang.ExceptionInInitializerError
at org.broadinstitute.sting.gatk.GenomeAnalysisEngine.(GenomeAnalysisEngine.java:167)
at org.broadinstitute.sting.gatk.CommandLineExecutable.(CommandLineExecutable.java:57)
at org.broadinstitute.sting.gatk.CommandLineGATK.(CommandLineGATK.java:66)
at org.broadinstitute.sting.gatk.CommandLineGATK.main(CommandLineGATK.java:106)
Caused by: java.lang.NullPointerException
at org.reflections.Reflections.scan(Reflections.java:220)
at org.reflections.Reflections.scan(Reflections.java:166)
at org.reflections.Reflections.(Reflections.java:94)
at org.broadinstitute.sting.utils.classloader.PluginManager.(PluginManager.java:79)
... 4 more

ERROR ------------------------------------------------------------------------------------------

ERROR A GATK RUNTIME ERROR has occurred (version 3.1-0-g72492bb):

ERROR

ERROR This might be a bug. Please check the documentation guide to see if this is a known problem.

ERROR If not, please post the error message, with stack trace, to the GATK forum.

ERROR Visit our website and forum for extensive documentation and answers to

ERROR commonly asked questions http://www.broadinstitute.org/gatk

ERROR

ERROR MESSAGE: Code exception (see stack trace for error itself)

ERROR ------------------------------------------------------------------------------------------

In fact, simply running "java -jar mutect-1.1.7.jar" gives me this error. My java version details are here:
java -version
java version "1.8.0_91"
Java(TM) SE Runtime Environment (build 1.8.0_91-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.91-b14, mixed mode)

Please advise! Thank you for your help.