PDF is not generated when page include image link from Jira issue

Summary

PDF export crashes whenever page contains image link referred from Jira issue 

Steps to Reproduce

Scenario 1 starting version 6.6.2 and above

1. Upload attachment to a Jira issue
2. Copy image address
3. On confluence, create a page
4. Insert Image using link copied from Jira image attached
5. Publish page
6. Export to PDF

7. Scenario 1 Actual results

   The below exception is thrown in confluence.log and PDF is not generated:

   2018-03-05 10:58:32,581 ERROR [http-nio-8090-exec-7] [atlassian.confluence.servlet.ConfluenceServletDispatcher] sendError Could not execute action
    -- url: /spaces/flyingpdf/pdfpageexport.action | traceId: 7d875de856d6047b | userName: admin | referer: http://192.168.100.102:8090/display/SAR/test+image+from+jiralink
   com.atlassian.confluence.importexport.ImportExportException: Exception while rendering the PDF document /atlassian-conf6/Home-directory/temp/pdfexport-20180305-050318-1058-7/SAR-testimagefromjiralink-050318-1058-8.pdf
    at com.atlassian.confluence.extra.flyingpdf.FlyingSaucerXmlToPdfConverter.convertXhtmlToPdf(FlyingSaucerXmlToPdfConverter.java:104)
    at com.atlassian.confluence.extra.flyingpdf.FlyingSaucerXmlToPdfConverter.convertXhtmlToPdf(FlyingSaucerXmlToPdfConverter.java:54)
    at com.atlassian.confluence.extra.flyingpdf.FlyingSaucerPdfExporterService.createPdfForPage(FlyingSaucerPdfExporterService.java:95)
    at com.atlassian.confluence.extra.flyingpdf.ExportPageAsPdfAction.doExecute(ExportPageAsPdfAction.java:40)
    at com.atlassian.confluence.extra.flyingpdf.ExportPageAsPdfAction.execute(ExportPageAsPdfAction.java:29)
    at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
    at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
   
   Caused by: java.lang.RuntimeException: Failed to read image
   

Scenario 2 prior to version 6.6.2 

1. Upload attachment to a Jira issue
2. Copy image address
3. On confluence, create a page
4. Insert Image using link copied from Jira image attached
5. Publish page
6. Export to PDF

Scenario 2 Actual results

PDF export successfully without image

Workaround

Upload the image as an attachment to the page and export to PDF again

Notes

• Export to Word is successful and includes the remote image.
• Related original bug for feature correctness and retrieving image can be found on new bug: CONFSERVER-55114