Creating multi-line comment with REST API

I am attempting to add a PR comment via the REST API and cannot seem to find a way to get Bitbucket to reflect multi-line comments. In order to be valid JSON, it must be a single line. However, Bitbucket does not seem to respect br tags, which are valid markdown. I cannot seem to find a way to create any type of comment other than “raw”.

For example, this does NOT work and displays the actual break tag text in the PR:
curl -X POST "<workspace>/<repo_slug>/pullrequests/<number>/comments" -u "<username>:<app_key>" --header "Accept: application/json" --header "Content-Type: application/json" --data '{"content":{ "raw":"line 1 <br /> line 2" } }'