class WebMock::Util::Headers

def self.normalize_headers(headers)
  return nil unless headers
  headers.each_with_object({}) do |(name, value), new_headers|
    new_headers[normalize_name(name)] =
      case value
      when Regexp then value
      when Array then (value.size == 1) ? value.first.to_s : value.map(&:to_s).sort
      else value.to_s
      end
  end
end