Summary

When an attachment is removed from an issue, the internal <JIRA_HOME>/data/attachments/ folder does not delete the created thumbnail.

Steps to Reproduce

1. Create an issue
2. Attach an image to it (More > Attach Files or Attach Screenshot)
3. Delete the attachment (click the trash icon at the thumbnail)

Expected Results

All the content from that attachment is removed from <JIRA_HOME>/data/attachments/<ISSUE_KEY> folder

Actual Results

The image thumbnail remains in the <JIRA_HOME>/data/attachments/<ISSUE_KEY>/thumb folder

Workaround

Manually remove the <JIRA_HOME>/data/attachments/<ISSUE_KEY>/thumb/thumb<XYZ>.png thumbnail file if there is no <XYZ> file at <JIRA_HOME>/data/attachments/<ISSUE_KEY>/ folder.