NullPointerException in RepositoryValidationInterceptorFactoryR4 when hapi.fhir.max_page_size is configured

[juergenbernhardt]

When configuring hapi.fhir.max_page_size, the application throws a NullPointerException in RepositoryValidationInterceptorFactoryR4.

Affected code:

https://github.com/hapifhir/hapi-fhir-jpaserver-starter/blob/master/src/main/java/ca/uhn/fhir/jpa/starter/common/validation/RepositoryValidationInterceptorFactoryR4.java#L53

It appears that results.size() is accessed although results can become null.

Additionally, this only seems to happen when the number of found results is greater than or equal to hapi.fhir.max_page_size.

If the number of results is below max_page_size, results.size() is not null.

steps to reproduce

configure

hapi:
  fhir:
    max_page_size: 100

expected behavior

The server should start normally and validation should not throw a NullPointerException, independent of the configured max_page_size.

version:
HAPI FHIR JPA Server Starter: 8.4.0

[steveswinsburg]

I have configured max_page_size to 1, loaded data (from AU Core Test Data) where I get 7 results:

http://localhost:8080/fhir/Patient?name=sofia&_summary=count

{
  "resourceType": "Bundle",
  "id": "0d2374cb-f935-44c3-bf79-10964ba1b632",
  "meta": {
    "lastUpdated": "2026-06-04T10:41:59.181+10:00",
    "tag": [
      {
        "system": "http://terminology.hl7.org/CodeSystem/v3-ObservationValue",
        "code": "SUBSETTED",
        "display": "Resource encoded in summary mode"
      }
    ]
  },
  "type": "searchset",
  "total": 7
}

Then running the search gives me a correctly paged response with 1 result per page.

Server starts up fine, no exceptions.

I note that to enable the class you need to set:

hapi:
  fhir:
    enable_repository_validating_interceptor: true

But that doesn't appear to make a difference in triggering the error.

@juergenbernhardt Have you got steps to reproduce, and have you tried latest version?