How to register extension on local HAPI FHIR Server

[Yi Luo]

I want to define an extension to be included in the patient resource type in DSTU2. I think using Undeclared Extension makes sense here. As mentioned in the FHIR website, all the extension should be registered in the StructureDefinition resource before use. Then, the question is, how can I fill the URL field? Or put it in another way, how can I register the extension on my local HAPI FHIR Server?

I have tried client.create().resource(StructureDefinition.class), but the create method is not applicable for StructureDefinition.

[Brad Solomon]

It seems like we've asked a similar question in https://groups.google.com/g/hapi-fhir/c/jRmqyuX9iEQ and I've been surprised at the lack of responses. Is this really not something that HAPI FHIR more directly supports?

The FHIR Extensibility documentation at https://build.fhir.org/extensibility-examples.html makes it pretty clear what this process *should* look like - defining the StructureDefinition and hosting it under your own FHIR server's baseUrl, then pointing back to that URL with the actual Extension.url. But HAPI FHIR does not have anywhere near a smooth way to implement this, either for "registering" the StructureDefinition or automatically tying the Extension.url back to it.