Can't run "bundle exec rspec" normally

[YujiKonno]

I built my pc's enviroment for pullrequest, referencing below URL (https://www.elastic.co/guide/en/logstash/current/_how_to_write_a_logstash_input_plugin.html). But "bundle install" didn't run normally in the "Add a Gemfile" section.

Gemfile source 'https://rubygems.org' gemspec gem "logstash", :github => "elastic/logstash", :branch => "5.3"

Run bundle install Fetching git://github.com/elastic/logstash.git Fetching gem metadata from https://rubygems.org/......... Fetching version metadata from https://rubygems.org/.. Fetching dependency metadata from https://rubygems.org/. Could not find gem 'logstash java' in git://github.com/elastic/logstash.git (at5.3@0e1bce8). Source does not contain any versions of 'logstash java'

And also tried to test below pattern.

gemspec file source 'https://rubygems.org' gemspec

Run bundle install Success

bundle exec rspec No examples found. Finished in 0 seconds (files took 0.289 seconds to load) 0 examples, 0 failures

It's little strange that "No examples found" appears although there are few test cases in _spec.rb.

Did you do anything special when you ran bundle install? or bundle exec rspec? Actually this is the first time for me to write ruby, I don't clearly understand how to setup.

Thank you for reading.

※My pc environment Windows 10 java version 1.8.0_121 jruby 9.1.8.0 (2.3.1)