Throughout 2018 and 2019, Atlassian will undertake a number of changes to our products and APIs in order to improve user privacy in accordance with the European General Data Protection Regulation (GDPR). In addition to pursuing relevant certifications and data handling standards, we will be rolling out changes to Atlassian Cloud product APIs to consolidate how personal data about Atlassian product users is accessed by API consumers.
A summary of all relevant API changes has been posted in the JIra Cloud Platform API docs:
https://developer.atlassian.com/cloud/jira/platform/api-changes-for-user-privacy-announcement/