module Mongoid
method String#to_a was removed in Mongoid
4 reference: github.com/mongoid/mongoid/commit/db84c0972bf4f01019cdfc2e9ab647fb814d3224
method String#to_a was removed in Mongoid
4 reference: github.com/mongoid/mongoid/commit/db84c0972bf4f01019cdfc2e9ab647fb814d3224