Intended behavior: Max number of search results for jpa maximum fetch size and prefetch threshold

[G-2-Z]

Describe the issue
In our custom HAPI FHIR server, which is based on the jpa starter project, we encountered inconsistencies when performing searches. When performing search operations for large quantities, such as fhir/Provenance?_sort=recorded, not all existing resources are returned.

We found that the max_page_size jpa starter project config parameter is not only used for the DatabaseBackedPagingProvider.setMaximumPageSize(), but also the jpaStorageSettings.setFetchSizeDefaultMaximum().
The total number of returned resources without changed config parameters was 2004 which as far as we know is based on the SearchPreFetchThresholds (default (13, 503, 2003, -1)).

There is some math going on in the classes building the SQL Querry that also adds one to the prefetch threshold and such that we did not totally unravel. We therefore would like to confirm, if the following is the intended behavior or not:

The HAPI FHIR JPA Server will return up to X resources for a single search where X is either the jpa storage setting maximum fetch size, or the highest prefetch threshold, whatever is higher.

If this is the case, we will open another ticket in the starter project to add another config parameter or make this clearer.