Building elasticsearch output plugin

Trying to test out a modification to the elasticsearch output plugin (https://github.com/logstash-plugins/logstash-output-elasticsearch), but I'm unable to get past the `bundle install` step with the current checkout.

https://gist.github.com/matthughes/c985d12defe52223ffbf

[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]
[ERROR]   The project rubygems:logstash-output-elasticsearch:0.1.19 (/Users/mhughes/OpenSource/logstash-output-elasticsearch/logstash-output-elasticsearch.gemspec) has 2 errors
[ERROR]     Unresolveable build extension: Plugin de.saumya.mojo:gem-extension:1.0.7 or one of its dependencies could not be resolved: Failed to read artifact descriptor for de.saumya.mojo:gem-extension:jar:1.0.7: Could not transfer artifact de.saumya.mojo:gem-extension:pom:1.0.7 from/to ccad-uber (https://acropolis/nexus/content/groups/ccad-uber/): peer not authenticated -> [Help 2]
[ERROR]     Unknown packaging: gem
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException
[ERROR] [Help 2] http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException
 
Errno::ENOENT: No such file or directory - /Users/mhughes/OpenSource/logstash-output-elasticsearch/deps.lst
An error occurred while installing logstash-output-elasticsearch (0.1.19), and
Bundler cannot continue.
Make sure that `gem install logstash-output-elasticsearch -v '0.1.19'` succeeds
before bundling.

Am I missing another step? I tried this on not just master, but the previous two releases of this plugin and they all fail so I don't think this was a recent breakage.