Expansion fails for ValueSet with no concepts or filter based on urn:ietf:bcp:13

[codeforgreen]

Expansion fails for ValueSet with no concepts or filter based on urn:ietf:bcp:13

For example:

{
    "resourceType": "ValueSet",
    "id": "custom-MimeType",
    "url": "http://example.com/custom-mimetype",
    "version": "1.0.0",
    "name": "MimeType",
    "title": "MimeType",
    "status": "active",
    "publisher": "Publisher",
    "description": "Attachment mime type supported by Publisher",
    "compose": {
        "include":  [
            {
                "system": "urn:ietf:bcp:13"
            }
        ]
    }
}

After storing this ValueSet, the expansion for it is automatically triggered in the background. That will result in the following error:
HAPI-0702: Unable to expand ValueSet because CodeSystem could not be found: urn:ietf:bcp:13

Caused by: ca.uhn.fhir.rest.server.exceptions.InternalErrorException: HAPI-0888: org.hl7.fhir.common.hapi.validation.support.InMemoryTerminologyServerValidationSupport$ExpansionCouldNotBeCompletedInternallyException: HAPI-0702: Unable to expand ValueSet because CodeSystem could not be found: urn:ietf:bcp:13
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.expandValueSetHandleIncludeOrExclude(TermReadSvcImpl.java:1040)
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.lambda$doExpandValueSet$2(TermReadSvcImpl.java:924)
	at org.springframework.transaction.support.TransactionOperations.lambda$executeWithoutResult$0(TransactionOperations.java:68)
	at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140)
	at org.springframework.transaction.support.TransactionOperations.executeWithoutResult(TransactionOperations.java:67)
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.doExpandValueSet(TermReadSvcImpl.java:924)
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.expandValueSetIntoAccumulator(TermReadSvcImpl.java:639)
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.lambda$doExpandValueSet$1(TermReadSvcImpl.java:560)
	at org.springframework.transaction.support.TransactionOperations.lambda$executeWithoutResult$0(TransactionOperations.java:68)
	at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140)
	at org.springframework.transaction.support.TransactionOperations.executeWithoutResult(TransactionOperations.java:67)
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.doExpandValueSet(TermReadSvcImpl.java:560)
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.expandValueSet(TermReadSvcImpl.java:532)
	at ca.uhn.fhir.jpa.term.TermReadSvcImpl.expandValueSet(TermReadSvcImpl.java:3074)