class Grape::Validations::Validators::ValuesValidator

def validate_param!(attr_name, params)
  return unless params.is_a?(Hash)
  val = params[attr_name]
  return if val.nil? && !required_for_root_scope?
  val = val.scrub if val.respond_to?(:scrub)
  # don't forget that +false.blank?+ is true
  return if val != false && val.blank? && @allow_blank
  return if check_values?(val, attr_name)
  raise Grape::Exceptions::Validation.new(
    params: [@scope.full_name(attr_name)],
    message: message(:values)
  )
end