class ActiveModel::Validations::AcceptanceValidator::LazilyDefineAttributes

def define_on(klass)
  @lock&.synchronize do
    return unless @lock
    attr_readers = attributes.reject { |name| klass.attribute_method?(name) }
    attr_writers = attributes.reject { |name| klass.attribute_method?("#{name}=") }
    attr_reader(*attr_readers)
    attr_writer(*attr_writers)
    remove_method :respond_to_missing?
    remove_method :method_missing
    @lock = nil
  end
end