Creates temporary avatar using multipart. The response is sent back as JSON stored in a textarea. This is because the client uses remote iframing to submit avatars using multipart. So we must send them a valid HTML page back from which the client parses the JSON from.

<p> Creating a temporary avatar is part of a 3-step process in uploading a new avatar for a user: upload, crop, confirm. This endpoint allows you to use a multipart upload instead of sending the image directly as the request body. </p> <p> You *must* use "avatar" as the name of the upload parameter:</p> <p/> <pre> curl -c cookiejar.txt -X POST -u admin:admin -H "X-Atlassian-Token: no-check" \ -F "avatar=@mynewavatar.png;type=image/png" \ 'http://localhost:8090/jira/rest/api/2/user/avatar/temporary?username=admin' </pre>