Deleting undefined page links using the JAVA API does not work

Issue Summary

Using the JAVA API methods com.atlassian.confluence.core.ContentEntityObject.removeOutgoingLink() and com.atlassian.confluence.links.DefaultLinkManager.removeLink() in a script is not working

Environment

• Confluence 6.15.9
• ScriptRunner for Confluence 5.5.11

Steps to Reproduce

1. In a test space create undefined page links in at least 2 different pages;
2. Open the Script Console under the Administration console;
3. Copy the contents of the attached Script.txt into the console;
4. Edit the space key in line 24 to match your test space;
5. Click on Run - verify that the output lists the different pages created and the undefined links created in step #1;
6. Open the pages listed on the output of the previous steps;
7. Go back to the Script Console and uncomment the code dlm.removeLink(link2) in line 37;
8. Click on Run.

Expected Results

The undefined links listed in the script output should be removed from the page.

Actual Results

After step #6 the page links are still present in the pages.
Running the script after step #Y just returns null and the below exception is thrown in the atlassian_confluence.log:

2019-09-24 13:37:02,768 WARN [http-nio-26156-exec-2] [runner.rest.common.UserScriptEndpoint] exec Script console script failed: 
 -- referer: http://localhost:26156/c6156/plugins/servlet/scriptrunner/admin/console | url: /c6156/rest/scriptrunner/latest/user/exec/ | traceId: 00b5911e85ae0161 | userName: admin | sr.execution.id: 587f7765-62a7-480a-bb03-ae1ddb5b9f33
java.lang.NullPointerException
	at com.atlassian.confluence.links.DefaultLinkManager.removeLink(DefaultLinkManager.java:73)
	at com.atlassian.confluence.links.LinkManager$removeLink.call(Unknown Source)
	at Script53.run(Script53.groovy:42)
...

Notes

The classes and methods in question are documented in:

• Class ContentEntityObject
• Class DefaultLinkManager

Workaround

Currently there is no known workaround for this behaviour. A workaround will be added here when available