Hello
It's related to commits:https://git.postgresql.org/pg/commitdiff/c203d6cf81b4d7e43edb2b75ec1b741ba48e04e0https://git.postgresql.org/pg/commitdiff/5d28c9bd73e29890cccd3f6b188b86f81031f671https://git.postgresql.org/pg/commitdiff/1c53c4dec3985512f7f2f53c9d76a5295cd0a2dd
Feature was reverted in master. Remains present in pg11, but nonfunctional and undocumented to avoid an ABI break for code touching relcache entries.
regards, Sergei