code: @Override
      @SuppressWarnings("checkstyle:linelength")
      public Page<AssignedAddOnExtension> firstPage(final TwilioRestClient client) {
          this.pathAccountSid = this.pathAccountSid == null ? client.getAccountSid() : this.pathAccountSid;
          Request request = new Request(
              HttpMethod.GET,
              Domains.API.toString(),
              "/2010-04-01/Accounts/" + this.pathAccountSid + "/IncomingPhoneNumbers/" + this.pathResourceSid + "/AssignedAddOns/" + this.pathAssignedAddOnSid + "/Extensions.json",
              client.getRegion()
          );
  
          addQueryParams(request);
          return pageForRequest(client, request);
      }
docs: Make the request to the Twilio API to perform the read.
  
  @param client TwilioRestClient with which to make the request
  @return AssignedAddOnExtension ResourceSet