The Cerner Ignite APIs for Millennium with Bulk Data Access provides system applications the ability to access large volumes of core clinical data for a group of patients in alignment with 21st Century Cures Act regulations.
The Group Export operation is available in our developer sandbox but as of now It is not enabled for clients.
All resources required by US Core Profiles:
http://hl7.org/fhir/us/core/STU4/general-guidance.html#us-core-data-for-interoperability except DiagnosticReport can be exported using the test groups documented in the developer documentation.