Seeing "$projectKeyEncoded cannot be resolved" in JIRA debug logs when open any page. Why?

[Geoff Wilson]

With the JIRA logging set to DEBUG (on our development instance, to note), I'm now seeing around 10 of these debug statements in a row each time I refresh a page, basically.  In an effort to clean up the logs and help understand if there's something gone wrong, what could be causing this output?

2017-05-04 12:28:23,049 http-nio-8080-exec-6 DEBUG jira 748x4769x1 1vm87zx xx.xxx.xx.xxx /secure/MyJiraHome.jspa [velocity] Null reference [template 'getEncodedBodyFromContent', line 1, column 33] : $projectKeyEncoded cannot be resolved.

[Łukasz Modzelewski _TTPSC_]

"ach time I refresh a page" maybe that refreshed page is the clue eg. if its some admin page it won't be associated with any project, and any projectKey so this would make sense "$projectKeyEncoded cannot be resolved"