renderedFields include Fields with Null values

Summary

• In JIRA 6.4.x (6.4.12 tested), renderedFields from Get Issue Rest API only include fields whose values can be displayed in HTML format (except a few special fields noted below).
• In JIRA 7.x (tested in 7.3.5 and 7.4.3), renderedFields include all fields, and those whose values can't be displayed in HTML format will display null.

Steps to reproduce

Hit this URL in the browser:

• <JIRA_BaseURL>/rest/api/2/issue/<issue_ID_or_Key>?expand=renderedFields

Expected behavior

1. Only fields whose values can be displayed in HTML format will be included in renderedFields
2. As per https://docs.atlassian.com/jira/REST/server/#api/2/issue-getIssue, the field values should be in HTML format

   renderedFields - field values in HTML format

Actual behavior

All fields are included and field values are displayed in an inconsistent manner:

• Only Description field value contains HTML tags
• Date/Time field values seem to be displayed in plain text
• Special fields such as Time Tracking, Attachment, Comment, and Worklog are displayed in JSON format
• Other field values return null e.g. Project, Issue Type, Sprint

Notes

• This seems to be a regression of JRASERVER-31418
• Looks like non-text fields (whose values can't be displayed in HTML format) return null
• /rest/api/2/search?jql=key=<issueKey>&expand=renderedFields has the same behavior