Bundle of type ‘document’ is used to aggregate Clinical Note and related resources in a single document in scope of C-CDA on FHIR implementation.
See FHIR Document

1. Create

HTTP RequestMethodAction
/BundlePOSTCreate new document

The operation outcome contains link to the newly created Composition resource.

2. Conditional create
This method also supports conditional create. To use it, you need to set additional header:
If-None-Exist: [search parameters]The only parameter is accepted ‘identifier’.

If-None-Exist: identifier=00025