Broken percent-encoding in link interrupts PDF export

Summary

Invalid escape character of percent-encoding causes "URLDecoder: Incomplete trailing escape (%) pattern".

Steps to Reproduce

1. Create a page (P1) containing TOC macro and heading in multi-byte chars
   • 
2. Create a page (P2) containing a link to P1's heading
3. Export the page P2 to PDF and confirm it works correctly
4. Edit the page P2 to make the link's URL invalid against percent-encoding
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   • The example below contains invalid percent-encoding

     http://confluence.localtest.me/display/SS/Linked+page#Linkedpage-%E6%97%A5%E6%9C%AC%E8%AA%9E%E3%81%AE%E8%A6%8B%E5%87%BA%E3%81%
     

5. Export the page P2 to PDF and confirm it complains exception
   • 

Expected Results

PDF export doesn't get interrupted by broken link in page.

Actual Results

The below exception is thrown in the logs/atlassian-confluence.log file:

java.lang.IllegalArgumentException: URLDecoder: Incomplete trailing escape (%) pattern
	at java.net.URLDecoder.decode(URLDecoder.java:187)
	at com.atlassian.confluence.extra.flyingpdf.html.LinkFixer.decodeTitle(LinkFixer.java:96)

Workaround

Fix the broken link. If you are trying to export space to PDF, it's hard to identify which page causing the exception. Refer How to identify which page facing unrecoverable error for those cases.