Empty user search results immediately following app installation

Issue Summary

Some apps need to perform post installation tasks which are dependent on user searches such as /rest/api/3/user/search. These searches return no results immediately after the installation of the app.

For context, also see https://community.developer.atlassian.com/t/empty-users-and-projects-from-rest-api-for-just-installed-app/39753.

Steps to Reproduce

1. Install an app that performs a user search immediately after receiving the app enabled event.
2. Observe the returned results.

Expected Results

The search returns results.

Actual Results

The search results are empty for a period after the app was installed. Subsequent identical searches return results after a sufficient period of time has passed.

Workaround

Re-try until search results are obtained.