`ReferentBasedDiscovery` is a reference discovery policy that is not set as the default. It has become outdated and properly supporting it in Serial/Parallel/G1 is non-trivial. A production failure was reported in relation to `-XX:RefDiscoveryPolicy=1` (which uses `ReferentBasedDiscovery`), as documented in https://github.com/corretto/corretto-11/issues/202.

To simplify the logic, it would be best to remove `ReferentBasedDiscovery` and the corresponding VM option, `RefDiscoveryPolicy`.