Fix validation on uniqueness of empty association
When Array#as_json and Hash#as_json are called without options, they
should also call #as_json on the children without options (instead of
nil)
Merge pull request #12774 from exAspArk/fix_uniqueness_on_relation

Fix validation on uniqueness
Merge pull request #13007 from chancancode/dont_call_as_json_with_nil

Don't call #as_json on children of Array and Hash with nil when no arguments are passed
Cleaned up app generator test
Using activerecord-jdbcsqlite3-adapter

PluginGeneratorTest needs to have
activerecord-jdbcsqlite3-adapter to pass under JRuby
Merge pull request #13010 from arunagw/cleanedup-generator-test

Cleaned up app generator test
Merge pull request #13011 from arunagw/jruby-fixes

Using activerecord-jdbcsqlite3-adapter
Helper should be a module in Rails guides [ci skip]
Merge pull request #13012 from harrigan/master

Helper should be a module in Rails guides [ci skip]