sunspot/sunspot — pull request #524 by christophemaximin (2013-12-24 09:31:02+00:00)
Title: Fixed deprecated (by ActiveSupport 4.1.0) require of "active_support/core_ext/object/to_json"

See https://github.com/rails/rails/blob/64c88fb5d2caf3c34742a07394ac68b8377c4936/activesupport/lib/active_support/core_ext/object/to_json.rb