code: def http_request_headers(instance):
      
      for key, obj in instance['objects'].items():
          if ('type' in obj and obj['type'] == 'network-traffic'):
              try:
                  headers = obj['extensions']['http-request-ext']['request_header']
              except KeyError:
                  continue
  
              for hdr in headers:
                  if hdr not in enums.HTTP_REQUEST_HEADERS:
                      yield JSONError("The 'request_header' property of object "
                                      "'%s' contains an invalid HTTP request "
                                      "header ('%s')."
                                      % (key, hdr), instance['id'],
                                      'http-request-headers')
docs: Ensure the keys of the 'request_headers' property of the http-request-
      ext extension of network-traffic objects conform to the format for HTTP
      request headers. Use a regex because there isn't a definitive source.
      https://www.iana.org/assignments/message-headers/message-headers.xhtml does
      not differentiate between request and response headers, and leaves out
      several common non-standard request fields listed elsewhere.