Problem Definition

The current REST API doesn't allow users to add an attachment while creating the issue.

Suggested Solution

Add a JSON field to enter a base64-encoded attachment when hitting the Create issue endpoint.

Workaround

1. Create an issue and capture the issue key.
2. Call the Add attachment endpoint.

Note(s)

The workaround doesn't help if the workflow has a validator to ensure there's an attachment at the time of issue creation.