brew/Library/Homebrew/cask/lib/hbc/utils/hash_validator.rb

module HashValidator
  def assert_valid_keys(*valid_keys)
    unknown_keys = keys - valid_keys
    return if unknown_keys.empty?
    raise CaskError, %Q(Unknown keys: #{unknown_keys.inspect}. Running "#{UPDATE_CMD}" will likely fix it.)
  end
end