Confluence fails exporting page to Word when the page links an image with "resources" in the URL path

Summary

If a Confluence page includes an image via URL, and the URL has the following text pattern in the path: resources/<sub-directories>/<image>, the "Export to Word" functionality breaks.

Steps to Reproduce

1. Insert an image on a Confluence page using a URL that has the image stored in a sub-directory of a directory called "resources".
   Examples:
   • <domain-name>/resources/images/image.jpg
   • <domain-name>/stuff/resources/images/jpegs/image.jpg
2. Save page
3. Click > Export to word

Expected Results

A prompt to save the word export file appears.

Actual Results

An immediate null response is returned from <confluence-base-url>/exportword.

Chrome:

Firefox:

Two errors are shown in atlassian-confluence.log:

2017-07-20 10:23:51,931 ERROR [http-nio-443-exec-8] [ContainerBase.[Standalone].[localhost].[/]] log Unhandled exception occurred whilst decorating page
 -- url: /exportword | traceId: 0fe81678df6ea33f | userName: jdoe
java.lang.NullPointerException
...
2017-07-20 10:23:51,933 ERROR [http-nio-443-exec-8] [[Standalone].[localhost].[/].[exportword]] log Servlet.service() for servlet [exportword] in context with path [] threw exception
java.lang.NullPointerException

Notes

• Export to pdf completes, but the image will not appear in the exported pdf.
• Issue does not occur if image is directly in the "resources" folder in the URL path (<domain-name>/resources/image.jpg)
• Last working in 5.9.14

Workaround

Escape the forward slash directly after "resources" with a backslash:

• <domain-name>/resources\/images/image.jpg
• <domain-name>/stuff/resources\/images/jpegs/image.jpg

NOTE: This workaround does not work if there is more than one "resources" directory in the URL path.