Publishing logstash-input-kafka yield a jar-dependency error?

[ph]

Logs from this execution:
Cloning repo
Switching branches
Running command

Warning: PATH set to RVM ruby but GEM_HOME and/or GEM_PATH not set, see:
    https://github.com/wayneeseguin/rvm/issues/3212

PWD
/tmp/studtmp-1728b07960ce6aa79128a8f92ade5691a5b56c0f55fd2c44424026bd134d/logstash-input-kafka
Warning! PATH is not properly set up, $GEM_HOME is not set,
        usually this is caused by shell initialization files - check them for 'PATH=...' entries,
        it might also help to re-add RVM to your dotfiles: 'rvm get stable --auto-dotfiles',
        to fix temporarily in this shell session run: 'rvm use ruby-2.1.2'.
Using /home/jls/.rvm/gems/jruby-1.7.22
Using /home/jls/.rvm/gems/jruby-1.7.22
Fetching gem metadata from https://rubygems.org/..........
Fetching version metadata from https://rubygems.org/...
Fetching dependency metadata from https://rubygems.org/..
Resolving dependencies............
Using rake 10.4.2
Using cabin 0.7.2
Using clamp 0.6.5
Using coderay 1.1.0
Using concurrent-ruby 0.9.2
Using diff-lcs 1.2.5
Using ffi 1.9.10
Using filesize 0.0.4
Using gem_publisher 1.5.0
Using gems 0.8.3
Using i18n 0.6.9
Using insist 1.0.0
Installing jar-dependencies 0.3.1
Using jrjackson 0.3.8
Using ruby-maven-libs 3.3.3
Installing ruby-maven 3.3.8
Installing jruby-kafka 1.4.0
  jar dependencies for jruby-kafka-1.4.0-java.gemspec . . .
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/maven/cli/MavenCli : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:401)
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:254)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
at org.codehaus.plexus.classworlds.launcher.Launcher.getMainClass(Launcher.java:144)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:266)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)

Errno::ENOENT: No such file or directory - /home/jls/.rvm/gems/jruby-1.7.22/gems/jruby-kafka-1.4.0-java/deps.lst
An error occurred while installing jruby-kafka (1.4.0), and Bundler cannot
continue.
Make sure that `gem install jruby-kafka -v '1.4.0'` succeeds before bundling.
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