Keycloak: Implement pagination support

[MisterTNT]

Dear project members,

while investigating a strange behaviour with two users beeing blocked in GitLab we found out that there is a limit for the results of a query via the api (see documentation https://www.keycloak.org/docs-api/22.0.5/rest-api/index.html#_groups => GET /admin/realms/{realm}/groups/{id}/members), which leads to this blocking while synchronizing...

Please provide a possibilty to override the default maximum results parameter (currently 100)...

Kind regards,
Thomas

[tjuerge]

KeycloakClient provides pagination support with a configured default page size of 100. But this method isn't used.

[tjuerge]

As it turns out the Link header-based pagination support described here isn't implemented yet. Maybe it will be implemented in Keycloak REST API v2.

So as mentioned in #8983 we've to implement paging by calling the corresponding /counts endpoint first and calculating first by our own. OMG :-(